That was probably my post. '70 Duster 8.75 rear and SS springs.

Stock Duster shock specs..

Extended 21.75"
Compressed 13.0"
Travel 8.25"

1986 Dodge truck specs (what everyone said to find)...

X-25"
C-15.6"
T-9.5"

Monroe 58577 coil over (I also have a set for my Cuda)...

X-22.5"
C-13.75"
T-8.75"

My buddy used a set of Monroe coil over 58496 on his Demon, but he has stock springs.

X-21.25"
C-13.00"
T-8.25"

We used a Monroe coil over 58577. I did have to remove the sleeve at the top to fit the upper shock bolt through. Two washers on either side compress the rubber washer inside.

With that being said, the stock upper shock mounting bolt was gone and it has an after market bolt in that place.

We also got a longer rear rubber brake hose for a 2 wheel drive Dodge truck. I don't remember the year but I think they're all the same.