This rep confirmed that the drive shaft is in fact for a TH400 or 4 speed manual tranny and they don't carry one for the TH350.  I pointed out that thier web site states it good for AUTO transmission but not limited to the TH400. They thanked me for the correction and said they would update the web page to note the correct application.

Since I had not installed it or got it balanced yet they would except it as a return and would send me a sticker that covered the return shipping cost through UPS.

Now my plan is to remove the old driveshaft and take it to my local specialist for new u-joints and cleanup and balancing. I guess I should have done that in the first place. ZIP products stands behind thier products and seems to be very fair even though the return time had lapsed they made it good and I will continue to buy from them.