1986 D21 4 wd conversion?

[gunsmith]

I have a 1984 720 4wheel drive that's been in an accident.  I'm looking at a 1986 d21 with a bad motor, but it is 2wd how big of a deal would it be to convert the d21 into a 4 wheel drive using the '84 720 for parts?

 

[Diesel Dentures]

Congrats on your awesome find man. Sadly I don’t have much input on the conversions other than driveshaft mods, but I know Charlie69, wayno, and datzenmike will have great info on this subject. If you ever change your mind and want to sell parts or have extras I would love to throw you some money for them ! 

[Diesel Dentures]

Also would love to see some pics!

[weldingrod]

Be further

ahead to put the D21 body on the 4x4 frame. Unless you are prepared to weld all the components to hold the front axle units the the D21 frame.

[bottomwatcher]

No! Hours and hours if you are a good fabricator. 2 scrap vehicles if not.

[datzenmike]

Is the 720 frame ok?

 

1/  Stick your Z24 engine in the Hardbody with the 720 electric fuel pump..... and just enjoy it.

 

2/  Swap the D21 body onto the 720 frame. The Hardbody has a wider wheel tread than the 720 so the wheels will look a little tucked in. Use the 720 wiring harness.

 

3/  Cutting all the 4x4 parts off the 720 and fitting and welding it all into a longer and wider frame? and make it work? Do 2/ above

[Charlie69]

I vote sell Diesel Dentures what he wants then sell the rest of the parts from both trucks and go buy the truck you want.  You could literally spend years swapping parts and then not be happy with the results.  Please do not set yourself up for failure in being happy with a hodge podge truck.

 

I am not saying you do not have the skills for this endeavor but do to the wider frame of the hardbody there will be a lot of fab work to get the 720 drive train in to the D21 2 wheel chassis.  By the time you finish this creation you will most likely have spent more than it would have cost to buy the truck you want.

 

I have played with the D21 frames and because of the width and other designs the use of the D21 frame under earlier trucks is not worth the work to me.  The 720 frames are the ones to use under the early 620s, 521s, 520s, and even the 320s (Stoffregen Motorsports narrowed a front clip from a 720 and installed it on a 320).

 

I have set 720 cabs and beds on the D21 frame and with all the mods needed deemed it not worth the trouble to morph the 720 to the D21 frame.  Now you are talking swapping the drive train yes it is doable but is it worth it?

Edited April 25, 2021 by Charlie69

[Stinky]

The short answer.... next to impossible.

 

They've already explained why.