did some math. man things clear right up... heres what I got. 5.29 R&P, 35's that measure 32.5" roughly OD, the trans has a O.D. Ratio of .838 from what I saw. SO...

-3k rpm; 65mph; 3,486 Dshaft RPM

-3.5K rpm; 76mph; 4,067 Dshaft RPM

As you can see the shaft RPM's are WAY up there when traveling in 5th gear over 3K engine rpm. hence why I have vibes I couldnt find. So either I should of done 4.88's, OR the Tires need to get taller, which I was planning on anyway. Now if you work backwards... let's say I can do 60mph w/out vibes to be on the safe side. that gives me a Dshaft rpm of.. 3,225 for a safe working vibration free limit. so with it in 5th gear, engine at 2,775rpm, having the Dshaft spin at 3,225rpm and be at the legal 70mph speed limit i'd need a 38" tall tire. WOW. that puts things in perspective. So either I have to put 37's on it, or throw 4.88's in it.

4.88's, 5th gear, 2,775 engine rpm, 3,225 Dshaft RPM and 35" tall tires would do 70MPH. And vibration free technically.

this is probly why most trucks (V8 trucks) have 4.56's, 4.11's etc and run 35's and haul ARSE 80mph down the interstate w/out problems. Another thing to think about is Joint angle. the higher the angle the slower the Shaft RPM can be w/out vibes. Phycics and math... they always come back to bite you in the but after it's all said and done. <img src="/forums/images/graemlins/drunk.gif" alt="" />