I have a '70 Blazer and am looking to replace the OEM 3 spd auto w/ a 4 or 5 spd auto. I keep thinking the engine's going to blow on the highway Does anyone know what is compatible w/ that year? I was looking at the 4L60 that was on the late '80's models. Can't get anything electronic as this was way before computers. Ideas? Please!

 

You will not find a 5 spd auto that does not have electronics. You can use a later electronic transmission, but the stand alone controllers are quite expensive (often more than the transmission if purchasing used).

I am looking at putting a 700r4 (or the later 4L60 non-E) into my 74 Blazer as well to keep it from grenading on the highway when I get it done. I am still looking into the logistics involved with making the conversion work as I still have not figured out if this would require a change in the driveshafts.