driveshaft problems

ok i found the problem the spring perches on the old rearend are 1/2" longer than the ones on the newer one. and when i jacked the car down the the driveshaft moved 1'' foward. so what should i do. i plan on taking the spring perches off the old one and welding them back on the new one that should solve my problem?? any thoughts would be great and thanks again.