Need Help Identifying Transmission

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Schwarzkopf9
Posts: 6
Joined: Tue Sep 10, 2019 2:51 pm

Need Help Identifying Transmission

Post by Schwarzkopf9 »

Hi guys, Im starting in on my diesel swap on a 1979 J20 manual tranny. Im trying to get an adapter plate but I need help finding what tranny is in it. I know there was a 3 or 4 speed offered that year for the manual but im not sure which it is. Its not drivable at the moment so I cant count gears, no label in the cab. the shifter is pretty sloppy so im not sure if im counting properly. Anyone know where I could find an identification plate on the tranny itself? Thanks for any advice!
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tgreese
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Re: Need Help Identifying Transmission

Post by tgreese »

There will be numbers cast into the side of the case for the two possible transmissions. A J20 probably has the Borg-Warner T-18, which will say "13-01" or "T-18." The 3-speed was a Borg-Warner T-15, which will have "13-07" or "T-15" cast in. Hard to mistake the two; the T-18 case is much larger, and the shiftr throw into 1st and reverse is very long. There is a spring in the T-18 shift top that collapses and makes it very sloppy.
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Topic author
Schwarzkopf9
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Re: Need Help Identifying Transmission

Post by Schwarzkopf9 »

Thanks tgreese! Ill check it out when I get home!

will e
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Re: Need Help Identifying Transmission

Post by will e »

Hey! Welcome to the board!
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tgreese
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Re: Need Help Identifying Transmission

Post by tgreese »

Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.

Topic author
Schwarzkopf9
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Joined: Tue Sep 10, 2019 2:51 pm

Re: Need Help Identifying Transmission

Post by Schwarzkopf9 »

Ok so according to the VIN and using the TSM (thanks for the link!) it appears to be a T-15A transmission.
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Stuka
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Re: Need Help Identifying Transmission

Post by Stuka »

I would not waste money on an adapter plate going to a T-15. I suggest finding a 4-6 speed manual that is sized correctly for whatever engine you are using, and has available transfer cases to match which ever front axle you are swapping in.
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Pablo
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Re: Need Help Identifying Transmission

Post by Pablo »

I second what Stuka said. That is not a good transmission for you. It is geared wrong and probably too weak for the torque you are going to be sending to it. Maybe goto the diesel conversions section and post the engine you are swapping in to get some advice? You should be able to find a 3-4 speed that will match your engine-- but those will not be overdrive transmissions. With a diesel it is really handy to have lots of gears and an overdrive. Without those gears you get out of the engine's powerband and driveability and fuel economy suffer.

If you are on a budget, there are usually non-desirable 3/4 speed transmissions that might work for your application. I bought 3 4bt diesel engines with T-19 transmissions hanging off them. I could not give any of those T-19's away, I think they went to the salvage yard. However-- if you use one of the 3/4 speed non-overdrive transmissions you will likely find that they are too short and you have to use an extension/relocation kit to move the gearshift mechanism further back (so it doesn't come out under the dash or even in front of the firewall). Newer overdrive transmissions are longer, so this is less likely to be a problem with them.
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rocklaurence
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Re: Need Help Identifying Transmission

Post by rocklaurence »

Also, shop around and find a Diesel/transmission/Tcase combo. You may want to consider getting a Driver-drop Dana 60 front axle that will match the newer Driver Drop Tcases.

Topic author
Schwarzkopf9
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Re: Need Help Identifying Transmission

Post by Schwarzkopf9 »

Ill be swapping in a Mercedes om617 turbo into it. I don't plan on throwing gobs of power on it, ill be throwing on the upgraded injection pump and new turbo. Should be able to put out 200hp easy, if not a tad more. As far as gearing goes, ill just have to play with that. I want to run a set of hummer miltary tires and so im thinking I'll re gear at 4.10 to start, depending on where the powerband is at highway speed(60-65). I got a good deal off mercedesdiesel4x4.com for the adapter kit about 450$ shipped. So far im about 900$ into my diesel swap, figure thats not to shabby, considering i cant even touch a 4bt for under 3k...lol
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