I also looked at your leaf springs and they seem to not be sagging, all of my trucks were 100k miles at least when i got them, one thing I noticed is they all had worn out and loose spring eye bushings in the springs and in the hangers themselves, the short wheelbase also needs a shock relocation kit and use 4 rear shocks since the wheelbase is so short in these crewcab trucks. Does your truck have a factory power steering unit or it is still manual?? As far as the 318 goes, it has enuff power to go faster than the sorry drum brakes can stop itlol I hope you have deep pockets and are part welder and fabber, these truck are so kewl and so under supplied in the aftermarket, there are no aftermaket power steering kits offered or disc brake kits due to the sorry closed nuckle dana 44, if you step up to a dana 60 you get discs and then can covert to hydaboost system from a newer dodge truck and then put discs on the rear dana 60 as well. This truck you have is one of the most unmolsted i ever seen inside, most have 40 holes from radios and extra bs and holes sawed fro non factory radios, great truck and dont stop converting it, you will never regret it for sure. I started on a 3.9 cummins and spicer 3053a 5 speed od with a sae#2 bell and Freighliner master clutch and misc into my 64 w200 and got stalled with the broken leg. Good luck and thanks for sharing the pics and story!!!