How did you remove the old ones? They look like they're glued in with something. They're all rusted but two are decent (the other two are beyond usability). I was able to totally remove the nuts on two rods and I cut the other two threaded rods right under the seized bolts to free the slipfitter clamps. I made sure I left enough to threaded rod remaining to use vise grips or whatever to grip them to remove them. Which is better, stainless steel or galvanized? The socket brackets inside the light are all galvanized. There's no rust at all inside the light and no stuck screws but the slipfitter clamps and the threaded rods and nuts were all rusty. The paint isn't in horrible condition either, as you can see. A little spotty on the sides and totally worn off on top but it's a gradual progression so it's not super noticeable. The door has pretty much all it's paint left, so the light still looks newish from underneath. I'm glad I finally have an L-150. They're really cool lights. I want to get my hands on a traditional OV-15 silverliner from the late 60s or 70s and them all have all three versions of the OV-15! (Tudor, this version, and the classic) Well, I guess three of four, if you count the Canadian ones. I think the odds of me getting a Canadian OV-15 are quite slim though lol. I'm still working on those R37s. No guarantees, but my friend and I are still contemplating it. The newly-grown vegetation is promising; it's providing more coverage than ether of us could have imagined. One of the lights it literally encased in the tree and might even require pruning to get to lol.

This one is fully encased in the tree. The area around the light is open, but it's got an umbrella of covering around it on all sides but the bottom.

This one will be the easier of the two to get, but it doesn't look as structurally sound lol.

The R37s are my top priority, but if I get those two, I will consider attempting to get a couple gumballs as well. One for me to keep and I'll see if my friend wants to mount the other one in his room. I want to rescue at least one arm but IDK if those screws are able to loosen or not. The poles are from the 1950s so I wouldn't be surprised if they're stuck in place. I might be able to fit a hacksaw between the two halves of the bracket to cut the bolts. Looks like there are two bolts on each side of the arm with one bolt on each side for the underbrace.

I tightened two nuts together on one threaded rod at a time to form a jam nut and turned the wrench on the bottom nut,a little penetrating spray beforehand might not be a bad idea,hopefully they will come loose, the "glue" substance could possibly be anti-seize compound,if that's the case the threaded rods shouldn't be too hard to remove. I would use stainless rod,nuts/washers,the ends of the rods won't rust where they've been cut,the galvanized threads are slightly larger and may be harder to install,when installing the new threaded rods repeat the jam nut procedure to tighten them in. That's great the fixture is in really good condition.
Yes it looks like the R37's would have good leaf coverage around them now,I wonder if a rope was tied above the deterioration half way up on the second pole if it could be pulled,crumbling the remaining concrete and bent in half to remove the light and arm from the ground,then it would be a lot easier to cut the bolts clamping the arm.

I tried tightening two nuts together and then turning the bottom one left. Nothing. I even stuck a piece of pipe around the wrench handle for leverage and nothing. I didn't put all my strength into it with the pipe though since I didn't want to shear the threaded rod, or else my only option would be to drill it out, which I'd like to avoid at all cost.

Hmmm...it might be a little tougher than expected to get them out. Keep applying rust release spray to soak in overnight,maybe do the reverse and try tightening in the rods to see if that will get them moving,as long as they're not already bottomed out,if no luck then it may require some heat from a propane torch.

I tried WD40. I sprayed it this morning and tried to loosen them tonight. No luck. Nothing budged with just the wrench but i tried and the wrench with the piece of conduit around it for leverage and all it did was move both bolts. There is definitely some kind of glue/epoxy/resin locking them in place since you can see some overflow of whatever the stuff is where the threaded rods enter the casting. My grandpa said he'll try vice grips but I wanted to see if I could get them off first. Wouldn't a torch melt the cast aluminum before the bolt gets hot enough?

I read somewhere that alum will eat away steel (but not aluminum) when soaked. Could that be worth trying? I was hoping to salvage one threaded rod to use for size when I went to the hardware store though. The other three I don't care about though.

Yeah it could be some type of thread lock on there then if the overflow is hardened. Elbow grease will be the only way to break them free. The propane torch won't get hot enough to melt anything,it only has to be hot (not red hot in this case) to help loosen the threaded rods,aluminum will expand with the heat faster than the steel.

I see. Yeah the overflow is rock hard and a yellowish brown color. So the best bet is to heat with a torch and then try loosening with a vice grips?

OK Darren, I went over my friend's grandma's house (half her basement is essentially my friend's workshop since his grandpa passed away three years ago) and got the hole drilled for the PC socket. The metal was an insane 3/16" thick! On the OVX, when I added the PC socket, the area to drill out was a mere sixteenth-and-a-half at most.

Also, while we were there, we got a small propane torch and a pair of vice grips. We heated up the part of the casting holding the rods and then I gave the rods a little persuasion with the vice grips and once that initial bind was broken, the rods spun out easily by hand (using a rag of course, since the rods were pretty damn hot lol). So I'll be getting some threaded rods and nuts tomorrow. Gonna get enough threaded rod (either one big one or small ones) for all four locations and then five nuts (one for each one and the extra to use to install the rods by locking two nuts together). I will get stainless. Stainless won't rust if it's cut, right? I always thought galvanized was better than stainless but I've heard some people swear by it and say galvanized isn't all it's cracked up to be so IDK.

Hey Mike, that's great they came out with some heat! That's correct,the stainless won't rust at all when cut like galvanized as the galvanizing is just a layer over the steel. Galvanized is really good to use if you don't have to cut anything or don't mind some rust if something is cut,it's also cheaper than stainless. Due to the galvanized nuts/bolts being slightly larger than regular plated and stainless nut and bolts galvanized may become really tight in the streetlight's casting right away, if you try threading a regular nut onto a galvanized bolt it will become tight after a couple turns. The only disadvantage is if stainless is over tightened then it can strip the threads a little easier than regular plated or galvanized fasteners,but that won't be an issue in the fixture.

I see. What makes stainless steel rust-proof? Do they remove all the carbon from it or add another ingredient when the metal is molten or something? How do you recommend I cut the threaded rod (assuming they don't exist in the perfect size I need them) into sections? Would an angle grinder work good? I need to make sure I'm still able to thread a nut on or thread the rod into the casting, so bolt cutters won't work.

Congrats on the OV-15 Mike
When I replaced the threaded rods in my OV-15, I used a hacksaw to cut it into sections. It wasn't too difficult. If you have a vice to clamp the rod in, that would make it very easy. A little advice, purchase 2 threaded rods. Cut from both ends so you can thread the cut end into the fixture and have the not cut end sticking out. I made that mistake the first time. It's not a big deal. It just looks better, and you won't have the sharp edges from the cut.

Stainless is an alloy with chromium blocking corrosion,yep a hacksaw will work or using a thin cutting disk in the angle grinder for stainless,it makes a nice clean cut. Yeah bolt cutters squeeze the rod and will distort the cut ends.

Thanks for the tip Ryan. The original plan was to cut them with my friend's angle grinder and then use a grinding wheel to smooth the cut ends so they're not sharp. As long as the tips aren't painted I'll do what you said though. If they are painted, I don't want the blue, green, orange, red, or whatever color paint on them showing.

Edit: sorry Darren, didn't see your reply I see. Maybe I'll try a hack saw and if I'm not feelin' it I'll use the angle grinder.

The new rods are installed (and so is the fixture!) They didn't sell stainless rods, so I actually just bought two ~6" stainless bolts, cut the heads off, and cut the headless bolts in half to get four stainless rods. It was a PITA since the hacksaw didn't cut perfectly clean. I actually did the opposite of what you suggested Ryan: I installed the factory ends into the casting since I couldn't easily get the cut ends to thread into the casting without stripping the threads in the casting since the threads got f*ed up at the cut. But it's all good now!

No worries Mike, glad it worked out good and the fixture is installed.

Nice job cleaning up that light Mike! Glad you were able to replace the threaded studs.

Thanks guys! Yeah I was surprised what a propane torch and a pair of pliers can do lol. They came out like they were brand new. And the threads were all shiny too, but lots of white power (cast aluminum corrosion I'd imagine) in the threads, which probably is what bound the studs up.

Ahh, I had similar trouble getting the lens tab screws off on my CGE signal but some penetrating oil and some heat made quick of those screws. I also had trouble with the screws on my M-250R CF but penetrating oil and a socket worked.

Yeah steel screws and cast aluminium threads don't really like one another, especially outdoors. The stainless bolts you put in will be a lot better.

What else might help with cutting the rod is a portable bandsaw like a Stout or DeWalt 20v cordless.

Anyhoo, I wound up drilling and retapping for some of the rods on my 4th generation OV25 and Crouse Hinds OV15.