shift pattern
 

I have a C-30 tow truck the transmission has a PTO coming off the flywheel for winch ... it appears to be the same bullet proof trany that I grew up with .. I have yet to dig into anything yet.. I am just getting it running after 20 years of sitting in a yard ... my question is ... I cannot find second... sitting parked I should be able to run all of the gears .... yet it goes into granyy fine pull straight back for second it seems blocked then into third ,fourth and reverse all seem fine ...anybody know what I should look for?

Re: shift pattern
 

See if the lever is blocked. I guess you have to delid the thing to find that out, though.

Re: shift pattern
 

Welcome....
Pto off the flywheel?....never seen that...
The gears may not be meshing if it's jjst sitting still..try moving th e truck back or forth a little and try it..
I'm assuming it's a sm465...

Re: shift pattern
 

Put it in neutral and get it running first and then try it. I bet it will work good if the clutch disk isn't stuck.

LockDoc

Re: shift pattern
 

I suspect what you think is first, is actually reverse. IIRC that makes it an NP420

Re: shift pattern
 

Welcome to the site. What Oldtown, Maryland?

What year is your C/30? As 68C15 mentioned, GM used different transmissions in this era (assuming we are talking 67-72) with two opposite revers positions. Left and up (forward) and right and down. And what Lock Doc suggests is also a very good possibility. Have you tried that? I hope you come back with results so that those who have offered help can know your results.

Re: shift pattern
 

yes pto is off the flywheel.... shaft comes from the bell housing ... along with lever/cable ... I have run it around the yard .... granny... no second into third then fourth stop and back up in reverse... I have driven /owned these 68-73 gmc and chevy trucks my whole life ... this truck drives... I have yet to do the brakes so I haven't actually taken it on road .... I have never had an occasion to open the tranny up before... I'm assuming there may be something internally blocking the shift lever but since ive never opened one was wondering what to look for...

Re: shift pattern
 

How about pics of the pto?

Re: shift pattern
 

Ok, so it sounds like you're n track, I agree. But to see which trans it is, what yer is the truck and where is reverse? Are you in MD or another Oldtown? Curious at first because my brother lives on Old Oldtown Rd near Spring Gap. And now because I have some transmissions I could help you out with. So the PTO is mounted on the bellhousing? I've seen that on heavy trucks, but didn't know of them for light trucks. I believe you, just curious about that. Off the flywheel give full engine power.

https://www.google.com/url?sa=t&rct=...eI9SO7W7e87H-f

Re: shift pattern
 

If it's either a SM420 or SM465 the top cover can come off. Remove floor hump first, then the trans top cover. Make sure you have shifter in N first so as to not get the gates out of time. Then it should be obvious what is blocking the 2nd shift.

It sounds to me like someone swapped in a different trans from a heavy duty (C40 and up) truck.

Can you post up a few pics of the trans from top, sides and bottom?