Trying to identify trans

wannabecummins

wannabecummins

Baloney Tugboat
Joined
Feb 6, 2010
Messages
124
Well I picked up a 91 GMC CCSB 4x4 with a 1992 12v in it. Was the a518 the only auto available in '92? Discussing with a friend of mine it appears to be a 727. There is no connector on the case for the o/d.
Here is a pic of the tail housing to help identify it.
49e7073e.jpg

Also this trans has a really bad flare shift from 2-3rd. Adjusted the throttle cable and adjusted the band on the outside of the case. Anything else I can do or is it time to replace the band?

Thanks in advance.

Brad (a.k.a "Perogie")
 
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It looks like a 727... But I dont know what a 4x4 A518 looks like either.

You can pull the trans and adjust the bands and line pressure on the VB. Over on DTR, there is a write up on them.
 
if its a 518 it will have a 2 wire plug by the shift linkage along with the normal 3 wire neutral safety\reverse switch, That looks like a 727 tail to me though it doesn't look thick enough to house the od unit. Red circle is the od plug.

I stole the picture from dtr sticky
 

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Thanks guys, kinda what I was figuring. Little dissapointed actually. Didn't realize you could still get a 727 in '92. Gotta figure out the flare shift and then start saving for a 47rh swap.
 
Ith

oldestof11 said:
No, you couldn't get a 727 in 92.
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Interesting. The I.D. Plate on the timing cover says 1992 on it. And it appears like the trans hasn't been separated from the engine. But it is all covered in oil so it's hard to tell. Guess this truck really is a mixture of all kinds of parts.
 
wannabecummins said:
Interesting. The I.D. Plate on the timing cover says 1992 on it. And it appears like the trans hasn't been separated from the engine. But it is all covered in oil so it's hard to tell. Guess this truck really is a mixture of all kinds of parts.
Click to expand...

Well the case would be the same just the output shaft, overdrive assembly/housing, and valve body are different. Someone may have had one rebuilt and had a bad case so they just used the first one the core supplier had.
 
Knoberman said:
Tranny doesnt need pulled for adjustments just pan
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Well it's booked in with the trans guy next week. He's gonna check her out and possibly replace the band. For what he said he'd charge me it's not even worth me messing with it :hehe:
 
he has to pull the pump to replace the band anyway so you may as well have him throw new clutches and seals in it
 
Mopar1973 said:
Well the case would be the same just the output shaft, overdrive assembly/housing, and valve body are different. Someone may have had one rebuilt and had a bad case so they just used the first one the core supplier had.
Click to expand...

I thought the cases where different on the 727 and the 518. I dont think the 727 case has oil feed passages for OD.
 
I believe the back of the case is different too, you can't put the od on a 727 because you can't bolt up the od piston assy. I don't have a 727 to compare to my 518 though.
 
The 518 and 727 use distinctively different cases, the overdrive unit will not bolt to a 727.
Also, never say never on the 3 speed in a 1992, they were actually installed in certain applications clear up into the late '90s (jet tugs).

Another cool fact is that in 1992 there WAS an option for 3.07 gears behind a 5 speed in a Cummins truck, of which I have seen two trucks that had the option.

Mark.
 
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