I had a spicer 7041. Had 2 unders, a direct, and an over. It was a pretty massive transmission, as large as your zf, and being cast iron, twice as heavy. I was going to use it strictly for the OD in my bus, but sold it in favor of different rear gears. I run an automatic, and don't think I will have an issue being geared too low out back.
You'd have to have a lot of space under the truck to mount one, and you'd likely have to have it after the transfer case, meaning you could only use it in 2wd.
Is your zf5 the close or wide ratio? If it's the close, I'd look for and upgrade to a wide version or a zf6. That will give you a better reverse and crawler gear then what you have.
Yeah, theres a couple of those on ebay. I’ve got an ext. cab with a long bed so theres a little room but not a ton. But ive seen guys put a 3 speed aux paired with their autos or 4 speeds in their f150s so i’d imagine it should be double, but i have no idea what they had for a 3 speed under those.
And yeah, i don’t mind it being just for 2wd anyway because theres gear reduction in the transfer case. The idea is to get gear reduction and overdrive for 2wd for towing and then for better highway cruising, which you can’t have both if you swap gears in the back.
I have the stock, diesel, “close” ratio gears in my zf5, and really i don’t want to touch those because i like the lower gears and the jump from 2nd into 3rd/4th/5th if i just swapped my drive gears would be too large for towing up hill and would be a bear. I already struggle with the jump from 2nd to 3rd hauling up steep, winding grades we have here in my town in AK, which is why a an aux tranny to split those gears would be nice.
The “close” gears were made for the idi, the “wide” ratio gears were for the gas trucks, and i want to keep it that way. A zf6 could be an option though. But, for the purposes of this thread i kinda want to stick to exploring the option of making a 15 or 20 speed setup in our trucks.
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