I don't want to replace all my gauges and I don't like the idea of spending almost $400 for a controller that feels like it will die in a couple of years, to get my speed signal from my 4L60 to my 86 IROC dash. So would like to figure out if it's possible to remove the stock speedo from the cluster and replace it fairly cleanly with an aftermarket electric speedo?

Anyone have anything? I believe the 91+ (92) have electric speedos, but that cluster is not the same.

Thanks
1986 Lt1/4L60 IROC