Identify which transmission I have on my truck and parts rigs

[PNW 720 97499]

I just lost 5th and reverse today in my 5-speed. How do I identify which tranny I have? I have two parts trucks, both with 5 speeds, one 2wd, one 4wd. I would prefer to use the 2wd trans, if possible to just swap the adapter and transfer case. Any thoughts or help is greatly appreciated in this. I was going to have a work mech pull the trans tonight or tomorrow night after work, and install this weekend ) if the other 4 gears hold up and I don't grenade the tranny). 

[datzenmike]

 Length. The 720 had 26" and 31.5" lengths so easier if they are the same length.

 

Ratios. Four wheel drive have a wide ratio with a lower first gear for a slower crawl speed. Two wheel drive are a mid ratio. They will work just fine in a 4x4 but if you seriously off road it you will loose some gearing advantage.

 

41 minutes ago, PNW 720 97499 said:

 I would prefer to use the 2wd trans, if possible to just swap the adapter and transfer case. 

 

?????

 

If both parts trucks have Z series engines, and if the length is alright, the transmission will drop right in, there is nothing to change.

[PNW 720 97499]

Thanks for the info! I was worried about having a married transfer case. I don’t do serious off road or crawling. More for snow and light off road

[PNW 720 97499]

Also, could I swap the end adapters if the lengths are different? How would I overcome the difference? Would I need to get the prop shaft lengthened/shortened?

[datzenmike]

The 720 uses a divorced transfer case so you can swap any transmission you like in and it remains uninfected.

 

Measure the lengths first. You cannot convert a 26" into a 31.5" length without also replacing the mainshaft inside. Forget about this.

[PNW 720 97499]

Damn, ok. I’ll take a look tomorrow. I appreciate the info. I think the Haynes is lacking in info...

[wayno]

The only time I had this happen was when a bearing out of the cluster gear bearing went thru the gears and broke the cluster gear shaft at the rear bearing on the rev/5th side, I lost rev/5th gears, the whole truck shuttered violently when it happened, it squealed briefly about a minute before, I turned around to go home as I was 5 blocks away from home, if I had stopped I likely could have rebuilt the transmission, but after that bearing went thru the gears it became a parts transmission, oil puked out everywhere as the rear case got damaged at the same time.

I learned that day that if it starts making really bad squealing noises to stop and shut it down, remove the drive line from the rear axle so the transmission does not turn, then tow it home and remove the transmission to replace the cluster gear bearing, if you drive it you can destroy the transmission.

 

Do you have a console in your truck?

If you do does it have a change tray in front of the shift lever, if it does you have a long shaft, if it does not have a place for change you have a short shaft.

[datzenmike]

Fifth and reverse are on the same fork in the rear case of the transmission. Maybe the roll pin in the fork sheared off, maybe the mainshaft nut came loose. (although it's now staked in place on the later 71B transmissions) Either way I would think fixable at the moment.

[PNW 720 97499]

So I have the short trans. My parts trucks both have the long trans. I have a long pulled out already. It seems as though I’m up shits creek. I’ll have to check the wrecking yard and see if I can work a deal out

[PNW 720 97499]

Also, before completely pulling my short trans, saw my problem: a nice hole in the side of the case. I was fortunate 2, 3, and 4 worked for two weeks. But at least now I have a ‘65 beetle to cruise while the truck gets fixed

[datzenmike]

If you use a long 5 speed maybe use that shorter driveshaft????

[PNW 720 97499]

The yoke doesn’t match, and I’ll need a console. Gotta check the junkyard’s pickup

[datzenmike]

The transmission splines should all be the same or you mean the differential yoke?

[PNW 720 97499]

Yoke to the transfer case of the prop shaft. The shorty has a larger diameter and different bolts. Junkyard had a shorty, but say it needs rebuilt. Any idea which trans number it is from the Haynes so I know which rebuild kit to get?

Edited May 29, 2019 by PNW 720 97499

[bottomwatcher]

Two universal joints is all you need to rebuild it. Several posts on u joints in the 720 forum.

[PNW 720 97499]

The prop shafts are different diameters and lengths overall. I was thinking just changing the yokes on the t-case if it comes down to it and I can’t rebuild the trans from the wrecking yard

[datzenmike]

I changed the receiver yoke on the trans case.