I replaced an SM420 which had replaced the stock column shift 3 speed with the T5 in my 54. The T5 is by no means a direct bolt-in, but has opened up a whole new dimension in driving for my old truck. I drive it every day, and can't envision my truck without the T5.
I guess it depends on what you want from your truck...if you've got intentions of driving on today's highways I don't think it can be beat!!! If you're planning on pulling stumps and putzing around town the sm420 is a good bet.
However, before you go jumping on any bandwagon, you need to understand that one change will inevitably lead to another. The gearing in an S10 T5 with a .72 or .86 OD will require getting your OD ratio, diff R&Pinion ratio, and tire height all matched up to where your engine is happiest!
There's a bunch of info on different transmission setups in this site....you've just got to figure out which way you want to go based on how much time and money you want to invest and your ultimate goal for your truck.
Dave
