[greg64]

reporter, wow there's a lot of interest in this topic. I have a 77 1/2 ton with a straight six, and 3.42 rear gears. Used to have a TH350 until it died. I really wanted to go manual, but at the time, there was no affordable overdrive stick. So I used an SM465. I like the 465 for what it is. The gear spacing is too wide (as others have mentioned), but when pulling a trailer, I like the granny low to get the load started. At 60 mph, I'm at about 2600 rpm. That's as fast as the old six wants to go.

Now, in my 64 suburban, I'm using a NV3500 from an early 90s truck. 5 speeds with overdrive and a lot better gear spacing. Also setup for a hydraulic clutch (both my rigs have hydraulic clutches). Wow, is that tranny ever smooth in shifting. I really like it. The only problem with it is that this transmission cannot be disassembled or rebuilt at home, the way a 465 can. It takes a lot of special tools (which I hate). It also takes special fluid (and different from the NV4500). I have a 283 with a torque cam, and with 31" tires and 3.73 rear gears, 60 mph is about 1700 rpm. Cruises along nicely, but I need to downshift to 4th for any significant hill.

The interesting thing is that the suburban is 1000 pounds heavier and is taller, but gets better mileage. A great engine/tranny combo. If I was going to do the rear end again (I've already replaced everything once), I'd use 4.11 gears to make 5th a bit better.

I love/hate the NV4500. No doubt it's tough, but there's the 5th gear nut problem (ya, it can be fixed), the super expensive and special fluid, and the gear spacing isn't any better then a 465, it just has OD.

The NV3500 is the best "cheap" option in my mind. If you can spend a lot more, I'd look at the TKO500, or a SM465 with a gear vendors on the back end. I dream of having an 8 speed SM465...

To me, the T5 is just too wimpy for full sized truck use. I had a T5 in an S10 years ago. It worked okay, but when you looked at it, it was clear it was a wimp.