Oh I so want to cry...stripped coolant threads!
 

Ok...I f:bang::bang:ked up.

I swapped my 700r4 with a 4l60e in my 84 vette. I also put in a ls6

Ok..while putting the coolant lines back on from the trans to the radiator, I think I screwed up the threads.

My 700r4 coolant lines appear to have flare 1/4" fittings in both sides. In my ziplock bag of parts marked trans lines I had two adapters. They appear to be 1/4 flare females to1/4 straight fittings. I thought these were the ones that went into the trans case on the 700r4....wrong! They threaded into the 4l60 just fine, and started getting tight, then they started getting loose again.....turns out this was the fitting from the radiator side.

So the thread size was right, but now I think the 4l60 case (2001) has a different pitch....it's 1/4" something....but not npt like the radiator side. Or maybe it's metric...I don't know anymore.

After removing fittings...boogered up threads in tranny case.

Does anyone know what size and type female threads are in the 4l60e case?
Any good way to repair them?

Helicoil. Is the Trans in the car?

Yes the trans is still in the car. It appears that I used the fittings from the radiator side :mad:

I am in agreement that the hole in the trans is 1/4 nps female. It appears that all I did is mess up the treads, which other people have cracked the case. So i guess I should count my blessings.

I'm going to try and use a 1/4 NPT tap and clean out the threads.

Anyone think I can just use jb weld?

no, like seriously......anyone think I can put some JB weld around the threads and it holds?

I guess it is worth a try as long as the JB weld doesn't get into the fluid.
Personally I would first tap it for the stock "straight" pipe, putting lots of thick grease on the tap to trap the metal. Since I run AN lines, I would first try AN straight-pipe adapters which have a sealing washer. If the threads were too loose, I would then try regular pipe adapters and just be sure not to overtighten them.

Or perhaps a premium thread sealant, as used on brake lines, might seal things up as long as the threads have some bite left.

I do think Helicoil is the proper fix.