TimmyG Posted August 3, 2019 Report Share Posted August 3, 2019 Hello, I'm new here. I've owned several 720s over the years and didn't know where to find a current online owners community. A friend told me about the site. Very cool. I've searched and come up with some info, but wanted to hear some thoughts. Current truck '85 720 KC z24 5 spd 2wd. I've learned that the 5 spd trans from 4wd 720s have lower gear ratios vs 2wd trans and bolts up to a z24.... but the 4wd trans case doesn't have the speedo gear, as it was run off the divorced transfer case. The diesel 720s (2wd only) came with the same lower gear ratios, correct? ...but I understand the diesel trans doesn't bolt up to a z24. I'm assuming the diesel trans has the speedo gear just like a 2wd gas truck. What would be needed to bolt up a diesel 5 spd trans to a z24? Are these diesel trans hard to find? Alternatively, could you put the 4wd gear set into the 2wd trans case? I'm thinking the speedo gear wouldn't cause an issue at the very least. I know someone is going to say what the hell am I even talking about doing and why....and that's ok. Lol Thanks for the help. 1 Quote Link to comment
datzenmike Posted August 3, 2019 Report Share Posted August 3, 2019 All 720 4x4 and the 2wd diesel have the wide ratio with the 3.592 first gear. Two wheel drive are mid ratio and 3.321 first. The 5 speed is a two piece construction sandwiching a steel adapter plate in the middle. If looking for this lower first gear just swap your tail and speedometer worm gear onto a 4x4 transmission. Only thing to watch for is the length. Unfortunately there were 26" and 31.5" 5 speeds. As long as the donor transmission is the same length this should be easy enough. The worm gear is held on with a C clip on each side. Clean the two mating surfaces and set the shift rods into the neutral position. Hold the striking rod turned to the 5th gear position, lower and wiggle into place. Here I put a bolt in the case and check that all gears are there. When sure, take the bolt out, pull up on the rear case and wedge it about 1/8" apart and add the sealer. Permatex 2 'Form-A-Gasket' makes a good silver colored one.. follow the directions. 2 Quote Link to comment
TimmyG Posted August 3, 2019 Author Report Share Posted August 3, 2019 Best reply I've ever gotten on a forum in my whole life. Wow. Thank you. 3 Quote Link to comment
datzenmike Posted August 3, 2019 Report Share Posted August 3, 2019 You should come here more often. 4 1 Quote Link to comment
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