I have 17x 10" Hoopster rims with 245-45-17 all around my 68 442. I have gone with 323 gear instead of 391 in the 12 bolt posi. Now it is much better on the street. I am wanting a little better on the highway, so I am thinking of putting 275 - 50- 17's on the back.They are almost 28" tall. Any imput on this wheel swap?

 

A 275-50 would fit perfectly on those wheels and fill the rear fender well out better. It will also raise the rear of your up a little but probably not enough to worry about. What did you do with the 3.91 gears? If you are going to sell them, I may be interested.

 

thanks for your advice. Sorry to say that the shop keep the 391 gears.