Duster Driveshaft length causing Vibration?

All, Just wanted to close this string out in case it helps someone else in the future. Here is a summary of details/specs/results:

1) Distance from C-C of my fully inserted yoke to the differential U-joint mount is 46-1/4"
2) Length of my original driveshaft was 44". (This WAY short driveshaft was not allowing my yoke to reach the bushing inside the trans casing, which resulted in LOTS of vibrations)
3) My shiny new steel, 3-1/2' dia., driveshaft fabricated by Republic Diesel in Louisville, Ky is 45-1/2" long. (This gives me 3/4" of travel between the c-c measurement above for installation and allows for full engagement of the Yoke into the bushing inside the trans. casing.)
4) I installed the new shaft yesterday and tested it on the road at ~65mph. My vibrations are GONE! car run smooth at highway speeds for the first time since I have owned it(~2-1/2 yrs). Problem solved...Hoo-Yah!

THX for the feedback and support. Also, wanted to plug Republic Diesel for their work and affordability(Total cost was $297.00). For this price, they re-used the 2 end pieces(U-joint mounts) from my old driveshaft, installed 2 new U-joints, checked the whole shaft-yoke assembly for balance, applied a nice coat of gloss black & had it done in a week.

-Scott