My 67's front seatblet retractors are shot. Theres no retracting to them at all. I found some new (springs tensioners retractors) whatever they are called, the metal cylinder piece. How hard are they to install? Ive never done it.

Not too bad...I heated up the plastic casing with wifies hair dryer before pulling the tensioner/belt out (just enough to get the asm out leaving the buckle end in the plastic). Pay attention to how they are assembled...mine had white oxide/corrosion inside..so make sure they are clean..I used a (very little) white grease.

Wind the spring about 4 turns to pre-load the belt at assembly otherwise the belt won't pull back in to the casing...

Mine woud not retract, but I removed the boot, spead the bracet, cleaned the mechanism, and wound a couple of extra turns on the spring. It's been working like a charm for 5-6 years, now

I'll try taking mine apart and rewind the spring. Is it pretty self explanatory once I get in it?

You'll find it's really self explainitory, no worries one of the easy projects.