The first half of your paragraph is interesting, but the second half has me going the wrong way. Not sure if you read my 3rd post above, but with what I believe is 3.73's in there now, is too low as it is. The truck revs way too high at interstate speeds.
I'm still learning on the 4-Speed project, as I know I'm not the first one out there to have one, but if worse comes to worse, I'll just install it on my present 3-Speed and keep it on the column.
By the way, although I am seeking more truck member input here, there are some interesting articles out there on it in some automotive publications I have recently discovered. I post them as time allows.
To the best of my knowledge and research, the BW OD came in vehicles that had 4.57 rear gears as it is a 30 percent overdrive. 4.57 x 0.70 = 3.199. It is darn near a 1,000 rpm drop from 3rd gear to 3rd gear OD. I have this setup in my truck with 4.57 rear gears. I wouldn't even consider running this setup with anything numerically lower than 4.57. From what I have read the only difference between a regular 3 speed case and one modified for the BW OD is the hole for the reverse lockout rod. The tailshaft lengths are the same, the yoke is the same, it is a simple swap from one to the other, but modifying a 4 speed case and fabricating the linkage is going to be a nightmare as already stated.
Mine is not setup with the relay, kickdown switch, etc. It is a switch on the dash and the cable to engage and disengage the unit. It works great, but there is no passing gear like it would be fully setup. The way people drive nowadays there is no need to pass as they are all going much faster than an old rig can go. Cruising at 65-70 on the open road while turning 2,400-2,500 rpms is nice, though.
