I'm getting ready to move on to upgrading the suspension after putting the 425 in my 83 Coupe. I'm having a little trouble figuring out what parts changed between 77-79 and 82-84. Looks like shocks stay the same, coil springs are different. I'm wondering about ball joints, I'm not sure which year's spec to order. Or if they are even different. Does anyone have any insight into the differences?
Looks like I found my own answer. Rock Auto has the same part for ball joints across those years. It seems like only the springs change with the different engine weights.
Ball joints and that type of stuff is all the same. At one point the shocks would have been different but they consolidated the parts a long time ago unfortunately. IIRC the steering boxes changed to give more "feel" as the years went on but again it is next to impossible to get a specific steering box for a given application these days.
I think my first thought if I was you would be to look at the springs for an 81 with the 6.0 liter engine. Its pretty close in weight and the rest of the body should be pretty close too.
For 79 RockAuto lists the same spring for 425 and 350 Diesel. For 80-81 they have a different part number but use the same spring for all three engines, 368, 350 Diesel and 4.1 V6. For 83 (my year) they list the same part number for the Diesel springs as for 80-81. I think I'll go with the 80-81 springs. And just to make sure, I need to change the rear springs to match new rate up front, correct?
Also, they list two kinds of ball joints, with and without cowl sill. How do I know which ones are correct for my car?
If you would have a master parts list, you could verify if Rockauto is right. I'm always very careful with the indications from Rockauto; they are often wrong.
Check and re check is always the game plan with RockAuto.