Thanks for all the good info. I have discovered that my 69 C20 has and Eaton rear. I will post a few pics this weekend. In using an online gear ratio calculator I had determined that I had 4.88, but apparently my Autogage tach may be a bit off or 40+ speedo - as they must be 4.56/57 gears.
I have an AX15 trans that I wanted to install, but thinking I still may need to try and find a 4.10 center section to get my rpm's to a comfortable highway cruising speed.
Dumb question, what's the easiest way for me to tell if I have the "no-spin" locker? And what should the width be on this axkle from mounting flange to mounting flange?
I like different, which is why I want to keep the Eaton, and rebuild the 307 - and keep this truck an 8-lug working truck. I would like to change out the coil springs - as this truck (when unloaded) has an extremely harsh jolt when you hit a bump. Anybody know what the factory spring rate would be for a coil sprung Eaton C20 LWB (base truck), so I can compare and get a slightly more forgiving spring? I also have aftermarket airbags installed on the axle so if I decided to load the bed down, I have extra help without the harshness day-to-day of these stiff coils.
But if I did find a 12 bolt that would direct swap in with no real mods and a better gear, I might consider.... So far only found a Dana 60 out of a ford and the guy says it is 74" wide, way to wide I think based on what I see so far. Of course, there's always the thought of doing a dually axle
