tranny question

I have a 61 gmc with the 305 V6. I am not sure what the tranny is but it pops out of second gear. could this be an easy fix or does it probably need to be rebuilt?
I am not sure but i think it is still the original tranny. Can anyone tell me what it is or how i can identify it?
Thank you

 

3 spd, 4 spd ??

 

yea sorry its 4 speed

 

Ahh, probably the original SM420, granny-low, 4-speed. They are rebuildable, however I have never done one. I have seen them for $50.00 or less on craigs list, so it may be more cost-effecient to replace with a good donor. Popping out of gear is not unusual on these transmissions.

 

Thanks. Yea if i can find one that may be the way to go.

 

Here’s an older thread that provides some ideas on what might be wrong:

http://www.pirate4x4.com/forum/showthread.php?t=25840

It still appears finding a good used unit may be the cheaper alternative, if one can be found.