the 3 speed with overdrive is what I have in my 1967, it is a 4 speed manual with 4th gear being like .8 to 1 if I remember right, it is what some people call a "toploader" it originally came out of a late 60's econoline van 2wd. the bronco websites sell a kit to convert it to 4wd with a dana 20. that one works great no plans to replace it. my question was actually about another bronco that I just purchased its a 1973. the 73 currently has the stock 3 speed and I am looking into putting a slop-o-matic into it, I found a c6 with whatever new process transfer case that came stock in a 1987 bronco in some local classifieds for $150, the guy just sent me a text back informing me that it is about 42 inches long. that's about 6 inches longer than the stock 3 speed and dana 20 so I don't know if I want to deal with it or not. I seen the bronco sites have kits to put the dana 20 on the c6 for a measly $500 or so , but they say driveline mods are still necessary. so I guess my next question is....... will a stock early bronco c4 bolt in in place of the manual with no mods?