My 70 dart thinks she's fat.

In my car I have a Dana with 4.88 gears. My sons 360 has an 8 3/4 with 4.10 gears, spool, and good axles. Not backbraced and stock caps. He tries to change out the ring n pinion every 3-4 years for preventative maintenance. He beats on it pretty good with a 727 and transbrake. View attachment 1715526643View attachment 1715526644
Bad *** ! Have you any experience with the 4.30 gears ? I have a 8.75 with 3.91 & was going to spool it but I also wanted to run a 28-29 inch tall tire & my cam is a 3400-7200 range& I should run 3800 stall minimum I'm told