[NuTuner]

Hi guys, got a problem. My beloved '85 GS is having problem. The rear end started producing these horrible grinding noises that I notice when I put the car in reverse and started backing down my drive way the other day .... I immediately turned the engien off and started to cry. Anyway, I think I need a new rear end. I have a GS, like I said before, and wouldn't mind upgrading to a Disk break rear axel, but at the moment I think I'm stickign with just another differential (monetary constraints). Could I upgrade to a GSL or GSL-SE rear end ? Is that possible, or am I stuck forever with the open-ended atrocity my car was built with ? Also, jumping from 3.90 to 4.10 might be fun. I'd appreciate any help you guys could give me. Thanks in advance.