Rear end cover bolt length
 

So my 102 came with a sleeve hitch installed, but the original trailer hitch is also there. Someone mentioned on here that the bolts on the transmission cover are too short to go through so much metal securely. Should I remove the trailer hitch to give the bolts more "bite" length? The sleeve hitch has a hole to drop a trailer pin in anyways, so I don't need both...

Sometimes I do dumb things, you can decide.
I'd determine whatever I wanted to bolt on there,
hold it in place, stick a 1/4" drill bit in the hole,
measure the depth from where it bottoms to the surface of your hitches, etc.
and use a bolt with enough threads that is 1/8 to 1/4 inches shorter than your measurement.
Hacksaw if you must, but that's me :TwoCents: input.

It most likely already has longer bolts in it. I would measure them like Ironman said. Make sure you don’t put bolts in that are too long, as the casting can crack when you tighten them up. You definitely don’t want that to happen.

Rear end bolt
 

Take a bolt that's a good 1/2 longer than the ones in it.Cut the head off,thread a nut or two if you have the extra length. Thread the stud in,nut down to plate,and the 2nd one if you originally picked out a real long bolt.Now carefully back out without moving the nuts.You have now the length, without measuring. But remember this is the absolute maximum.Too long of a bolt,you will strip or Crack cast iron.A thread chaser not tap is also another tool to clean up threads in the rear end housing.Wire brush the bolts if you reuse the old ones.If this is a new purchase,you can't be sure what the p.o.did.And leave the impact on the shelf,a ratchet you can feel much better the proper bolt tightening torque

Screw, 3/8-16 X 1-1/4 C-Z Hex Hd Cap. This is for the draw bar, and hitch link bracket. you need 3 If you have the 2nd outer hitch bracket you will need Screw, Hex Cap, 3/8-16 X 1.50 Lg.