Hmmm, if you have a stock BOP in your car now and an 8.5 sitting on the garage floor, can you measure them to get the difference in length from the end of the yoke to the centerline of the axle? If indeed the 8,5 is one inch longer than the BOP 8.2 they could make the shaft one inch shorter like you suggested. Would be wise to confirm the one inch first. Also tell them the size of the U-joint so they can weld in the correct yoke onto the back of the driveshaft.