Well maybe once and for all. Yes I did a search and got a phone book of misc info and opinion but nothing technical. I know the classic 4.11 gear and Zephyr combo was nice for a long wind up in lower gears. I'm not sure how much better or worse a pretty stock 59A will behave with 3.78s and Zephyr gears. The tires are 7.00s, and I'm not sure it's worth the effort if I can shag a trans at a good price. Then there's the year thing. What Zephyrs had the better/desireable gears? Any difference from Ford stuff? Specific years to look for/avoid? Surely this is a common and popular swap but I've simply never done it. Before I cover up the trans and such now would be the time in my 39 Std. Thanks in advance.