on the subject of steel versus aluminum. feel free to elaborate. i use aluminum, and i've never had one fail. i have several acquaintances with faster cars, and they've never had one fail. drums, yes. planetaries- no. thanks bg for getting me wondering if i need to bother with steel.

planetary material single choice
	i use steel
	i use aluminum
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i have had aluminum planetaries with severe spline wear, so i went with steel. i know a failure would cause a lot of damage, but i haven't any problems. i just made sure drive shaft was balanced, drive line angle is correct.

well I can tell you I have seen a number of aluminum ones lose there splines on plan old street driven cars and trucks,so anything with good hp is a crap shoot.

i wonder how much of that is from worn splines. i've done many where the spline fit is sloppy, so i change the planetary, the shaft, or both. i haven't had any failures. nothing faster than 10 second cars, though.

i respline the 618 trans 5 pin planet to fit on the older output shafts they will killthe splines on a heavy [3500+] car going in to the nine sec range!Mine broke on my second pass in the nines on the bottle soon as i pulled second gear KAAPOW !!! that was 15yrs ago ! but the stock ones are suprisingly strong, ive done lots of transmissions that are in 10 sec cars with stock parts !!!