on monday I had a true trac, 4.88 gears and new axles installed in the rear of my K5. I have 35" tires but only take it off road once in a rare while. My uncle owns a trans shop, so I had him and his other mechanic do the work. They were impressed with the planetary gear setup that the unit used. They thought it would hold up well to my use. I have not tried to make the wheels slip yet as I want the gears to break in properly before hammering on them. I bought my stuff from Randy's ring and pinion. They claimed the tru trac would be fine for my use. I opted to rebuild my 10 bolt vs swap to a 14sf. Most people say that is a no no, but I only put a few thousand miles on my K5 per year and I needed a lower gear than what a heavier axle would have had anyway.
Most people had good things to say for the true trac but of course there were a few that claimed to have them fail. Time will tell.