I'm in the process of putting a Dana 60 in my 440-6 4-speed RR--will the 30 spline axles hold up behind +/- 500 HP ? Or do I need to bite the bullet and change to 35 spline? Car is mainly street driven but does occasionally hit the track with drag radials.

With the way you drive, you may need 40 spline axles and a spool to make it live.

30 should be fine at that hp and weight

If it were me, I would change to 35 spline, but at 500hp you dont need to. but if more HP is in your future, than do it and be done.

My guess is for mainly street and only occasional strip, the 30 will last a very long time at that power level. But if you are buying axles, spool, etc. get the 35 spline.

I'd go up to the 35 spline now and do it and forget about it...thats what im doing with the Dana Im putting in (I know a place that is the cheapest for the internals kit, let me know if need the address). If your buying axles now its the same price, just gotta add in the extra for the internals kit

I twisted 30 spline mosers in my 8-3/4 in a mid 13 sec. stick car...Albeit i had wheelhop, but it still happened...go bigger now and avoid any possible problems later, especially with that power and 4 gear

35 spline internals match the strength of the rest of the rearend. The price of conversion parts is also reasonable.

I stock new 35 spline axle packages for $300 (assembled), complete 35 spline power-lock internal parts kits for $175 (including clutches) and light weight spools for $125.

I buy directly from the manufacturer in quantity. No middle men are involved.

hey doc dif do you have a web site or online store

never mind i googled it

My website is very out of date. I carry/produce many other brake, suspension and drivetrain products than what is listed.