[cleszkie]

I've done this exact swap. I am assuming that your Blazer is 4x4. If not then some of my responses may not be accurate.

1) Your speedo drive will be on the NP205, not the SM465, so it doesn't really matter if you have a drive on the tranny or not. A tranny from a 2x4 truck will have a fixed yoke on the output shaft. You would need to change the output shaft in the tranny to get the correct 10-spline output needed to duplicate the stock setup.

2) I am not aware of any differences between the 1/2 and 3/4 ton truck versions. However, I believe there is a wide-ratio version and a close-ratio version. The wide-ratio version has the super low granny first gear, and the close-ratio has "normal" first gear ratio. Basically, you start out in 2nd gear with the wide-ratio version and only use the granny gear for starting when pulling really heavy loads, plowing, or crawling. With the close-ratio version, you start out in 1st gear. The wide-ratio version has bigger gaps in gear ratios need to get to the 1:1 4th gear from the granny 1st gear.

3) Yes.

4) I am assuming that you are referring to the spring weight in the pressure plate. Typically, heavy springs will give you more clamping pressure to the clutch disc preventing slippage. But this usually comes with a stiffer clutch pedal. If you will be towing, plowing, mudding, or generally hammering on the go pedal, a heavy duty pressure plate may be what you want.

5) Yes. That is, if you are going for a stock SM465 to NP205 setup found in these trucks. That 10-spline output is coupled to the NP205 10-spline input via a female 10-spline coupler that resides within the adapter between the two cases. However, there are other, newer SM465 to NP205 combos that have different mating requirements that I am not schooled in. Others may provide that info.

6) You will need to swap in a 10-spline input shaft to work with the coupler discussed above, if you are going for a stock 67-72 setup.

7) There are steel and aluminum SBC bell housings available for our trucks. I went with a steel version. Both should work fine. If its a SBC bell housing, it should have provisions to bolt on the SM465.

8) No. If you go with the stock SM456 to NP205 setup, the transfer case will mount in exactly the same position as it is with the TH350. The TH350 is the exact same length as the SM465 with the adapter.

9) High hump 4x4 with openings for the SM465 and NP205 sticks.

10) The 67-72 4x4 SM465 shift lever has only a single bend. The two wheel drive versions have two bends, as do the later model 4x4 sticks.

One thing you need to be careful about is selecting the proper z-bar, frame side z-bar mount, and engine side z-bar ball stud mount. There are different versions for 2x4, 4x4, I6, and V8 applications. They are not interchangeable, trust me!