Stuck between two 620's

[rushkd]

100 on all 4 sounds like the tester (or testee) isn't working right. 100 isn't that good. It will run evenly though with all the same I just find that all the exact same number is suspicious.

 

 

They were not all exactly 100 they were all around plus or minus one or two or three PSI I was rounding it

[rushkd]

The engine will be getting a fresh up before It goes in. I like the body swap ideas

[Lockleaf]

Body swap is highly difficult between those frames. Look at what datnasty has had to do to fit a d21 frame under his 521. 720 and older frames interchange ok, but they totally redesigned the frame for the d21. You have to seriously body drop just to be at stock height.

[Charlie69]

That's one possibility. Swapping the 620 cab and bed over to the hardbody frame would give him 15 years less wear and tear, plus all the new front suspension and brakes.

 

The two downsides to doing a body swap are that now you've lost some of the originality of the vehicle and second,  technically it needs to go through DMV with all the new info. Here in CA, a frame swap will cause a pre smog vehicle to have to go through annual emissions testing. If you can make a solid case for repair using the newer frame, DMV has the power to let it slide.

 

Before doing a frame swap, a good plan is needed. Take good measurements of both vehicles before disassembly. Measure wheelbase, wheel centerline position inside the wheel opening, distance from back of cab to front of bed, distance/height of body mounts on frame, etc.

I put my 520 on a 720 chassis and will run it through AZ DMV to register the frame amd engine numbers to my 1966 520 title so I can travel through California with no worries that I do not have matching numbers.

[Charlie69]

I think the D21 chassis could be used easier than Datnasty did it as he 4 linked and did other work to it.  But the 720 chassis is by far the easiest swap to up grade the chassis, but he has a D21 siting there.

 

I mounted the cab to the chassis first and then I cut the bed mounts off of the 720 chassis and set the bed over the chassis bolcked it up to the level I wanted and then marked the 720 bed mounts and cut them down.  I then bolted the 720 bed mounts to the bed and lowered the bed onto the chassis and checked the bed for height and cab spacing and my brother tacked it in place I re checked the bed fitment and found the I needed to lower 1 mount an 1/8 of an inch.  This is how I did the bed.

 

Trimmed 720 bed mounts tacked on for the 520 bed

[Lockleaf]

I think the D21 chassis could be used easier than Datnasty did it as he 4 linkenked and did other work to it. But the 720 chassis is by far the easiest swap to up grade the chassis, but he has a D21 siting there.

 

 

While true, his first few posts about cab fitment talk about how sitting on the mounts, it looks like it's body lifted. He recommended d21 only for 4x4 swap because of that

[Stoffregen Motorsports]

Did he have to raise the floor? Or lower the mounts on the frame?

 

If the latter, that's par for the course when doing cab swaps.

[Lockleaf]

Raised the floor. It wasn't the mounts in the way, it was the frame shape.

[Lockleaf]

All that being said, you already have both, so i would say try the body swap. At worst you've wasted a few hours of work to look into how difficult it would be. At best you get major advantages

[Charlie69]

The main difference I see with the D21 Hardbody rolling cahssi is how high the engine and trans sit Nd how high the tail of the frame under the bed is.

 

1991 D21 Datnasty

 

Inside 1991 cab Datnasty

 

Here is a 521 frame stripped of front steering and suspension mounts.

 

[Stoffregen Motorsports]

I'm not seeing it either. The frame profiles are similar.

[Stoffregen Motorsports]

One possibility is that the newer frame is much wider at the cab...? I wonder if that was the problem with datnasty's fitment.

[rushkd]

Thanks for all the information guy. Still not sure what I want to do and which one I want to go with But I think I'm leaning towards the 74.

[rushkd]

I did some work this evening there is one small spot on the pan i will need to repair.  

 

 

 

 

 

 

[rushkd]

well as you can see im going with the 74 only because is was the first one i had and the parts cab is a 74 as well. on a side note i do not plan on striping the 76 of all its good parts. the only thing i need off of it is the hood. 

 

 

so i got the cab off the 74. i just need to pull the bed, engine, and a few things off the frame and hopefully i can get it all to the sandblaster in the next week or so.   

 

 

 

 

[racerx]

Man, if u finish this and get it running right, hats of to you.