Standard three speed trasmission stuck in first gear

[meathead42]

I have a 1973 454 Chevy k20 pickup that was stuck in first gear. I pulled out the shifter because I figured it was broken but it was fine. I then shifted the transfer case into 4H and the truck started shifting ok. Is this a coincidence and there is a real problem, or is there linkage from the transfer case that locks the tuck into first gear? I had a CD case stuffed in between the seat and 4WD shifter that could have moved it up a bit. This is the transmission that has the grandma gear and then three other gears.

The truck does not get driven much but when it does it pulls a trailer to the hills and I would hate to have that happen in the mountains. Any info on this transmission would be appreciated!

Thanks!

[Prong]

The transmission is a SM465. These things are bulletproof as long as you don't run them out of oil. Check that. If it's low add some 80-90W gear oil. It sounds like the transfer case is a NP 205 (equally bulletproof) Check/add oil to that as need be while you're at it. Was it stuck in granny gear (1st) or 2nd? If it was stuck in granny gear it may have bound up, because frankly the granny gear isn't good for much unless you're trying to pull a house down with it.

[meathead42]

Well it was second gear and the transmission is full of fresh new oil of the same you called for. I know they are bullet proof, but that is why I am confused. Why did it get locked into gear...

[86c20]

sometimes the way the grears on the sm 465 mesh make them hard to shift and if it is a np205 they have to be rolling to get out of 4low. i have had one for 6 years now and it has done this a few times and i found if you rock the truck alittle it pops out fine. i think it is the syncrows not lineing up right. these will not do it in low do to the cut of the teeth.

[meathead42]

I am just concerned that the truck will become locked in second gear again because I cannot explain what happened. It was stuck in second gear but the shift lever was up in the neutral position and could be moved left to right like it was in neutral, but not up or down. I had to be towed home because the truck over heated as I could not get any air though the radiator on that gear. Someone removed the shroud so now I got to find another one.

One of the things I did was rock the truck back and forth then shift the transfer case from 2H to 2L then the shifter started working again. Is it ok to drive the truck on dirt in 2L and use all the gears 1~4th? Not that it would be needed I am just trying to get this truck figured out.

As for the oil can someone confirm that the proper oil level is fill the transfer case and transmission up until it starts to come out of the fill hole and then cap it off?

Thanks everyone for your patience!

[86c20]

this sounds dumb but fill it to the top of the bottom of the hole. so fill it till ti just starts to come out the fill hole. it sounds like the shift forks inside may be messed up but it is something binding in there, you sloud be fine running on dirt in 4lo or 2lo if that is what you have. from what i have been told these trans are ez to rebiuld but i have not done one yet. how many miles are on the trans?