I bought a 1996 Impala about 8 months ago. I only have driven it about 300 miles and the transmission is starting to give me problems in 3rd and 4th gear. I decided to rebuild the tranny. When I removed the transmission I noticed it said 8SHD, which I believe is from a 98 truck. I already order parts to rebuild the tranny with a builder, but we ordered for a 96 Impala. My question is are the replacement parts interchangeable? Is the 98 4l60e worth building or should I find 96 4l60e core to rebuild? I really don't know much about transmissions. Any help or suggestions will be greatly appreciated.