620 on a 720 frame??

[Billy Dat Kid]

I'm about to do a 620 4x4 swap as well. I bought an '85 720 LWB 4x4 frame and will be putting my '77 620 KC body on it. I'm a ways away from actually setting the body and stuff on it, so what are the left and right box mounts that need to be moved?

As far as the drive train goes I'll be using my L20B and a normal 620 5spd if I can find one (otherwise I'll just keep the 4spd in it). I don't really want the ZX turbo or the 81-83 close ratio trans because I plan to run 31" tires and with the super tall OD gears, I'd be lugging the engine at 55-60 (which is where I almost always drive). So the .86 OD in the normal 620 5spd is enough. The front and rear shafts are in place already so I'd just have to have one make for my engine/trans setup and get all the lines and stuff run.

When i have the body off and get ready to pull the engine and trans, I plan to redo the rear main on the L20b. No sense in the clutch getting fried in 5k miles after having everything apart. Anything else you guys come up with is appreciated. Thanks.

[datzenmike]

If the 720 has a king cab on it's frame probably you won't have to do anything. I put my '78 KC on an '82 (2d) long bed frame. As the KC has a short wheel base box it wasn't long enough to sit on the very front two box mounts. I cut them off and moved them both back about 9-10 inches I forget. Probably could have just cut them off and left it. There's plenty of support.

 

The rear main seal??? This is what I would replace. Be sure to oil the seal lips so it doesn't start up dry.

 

Might as well replace the oil pan gasket while it's out.  

 

Oh, also the $5 pilot bushing in the end of the crankshaft. They are permanently lubricated so don't oil or grease them as this will collect clutch dust. A new release bearing. Just good insurance.

 

These parts are relatively cheap but a bitch to get at and replace later.