'91 K1500, 700R4 won't shift into 3rd or OD

[ct91rs]

I have a 1991 Silverado K1500 with a 700R4. The truck has 142k on the engine and trans. It shifts into reverse, 1st, and 2nd fine but the engine just revs and doesn't catch 3rd.

I don't know a terrific amount about transmissions but I've pulled a few 700R4's out of Camaro's in the past.

I've been looking around on message boards and I'm guessing the 3-4 clutch pack is bad. I found another used 700R4 4x4 trans that I could swap in but it doesn't look terribly fun.

I've read in another post that it could be a stripped govenor gear or stuck governor weights? Can anyone describe this to me? Where it is, what to check?

I'm going to drop the pan tomorrow to check for metal or clutches laying around. If I don't find anything, could the 3-4 clutch pack still be the problem?

Any ideas on what else might be causing this problem that I should check before pulling the tranny?

I really appreciate any help on this. Thanks much in advance!

[Schurkey]

If you had a defective governor, I'm thinking the trans would never shift into second gear from first.