I've added SCX uppers to my 388 Hustler and was wondering if anybody knew how much more weight the upper and 3 more quarts of oil adds per drive.

Maybe check the Imco site, a guess would be 50 lbs

are you running a sport master or sc lower, I read that the complete scx drive weighs 80 lbs more than an XR and is set back 3/4 of an inch

Is there going to be any speed loss going from a XR upper to the Imco scx upper ? There’s probably a lot of variables in that question but is there any real #’s one has lost going to the scx upper ?

Definitely a loss,

I thought there was zero loss unless you used the fat lower...

thats my understanding also

F-2 - Im running sport masters. Thank you for that info.

Larger gears, shafts, cone clutch, more lube, bigger cavitation plate, more drag, heavier, harder to turn. Possibly a necessary evil if you're blowing XR's apart.