GSL vs. GSL-SE Rear End?
 

Are there any visible external clues that will let me know which rear I have?

It's in a 79 Rx-7 with rear disc brakes.

thanks

Easiest would be the stud pattern. If it has 1st gen. rims on it then that will tell you whether it's a GSL or SE. If it has aftermarket rims you can measure it. SE is 114.3mm x 4 and non-SE is 110 x 4.

Externally, you can only tell the difference between an '81-'83 axle and the '84-'85 axle. The '84-'85 unit is bigger and MUCH heavier. That is what prompted me to use a housing from an '81 model, since adding unsprung weight really didn't appeal to me.

The pumpkin itself does differ between SE and non-SE models, but only internally, and are interchangeable in the '84-'85 axle housings. Also the driveshaft is different on the '83 and up models, so unless the guy who converted your car to rear discs used a later driveshaft as well, you probably have a '81 or '82 axle housing.

SE's have vented rear disks, GSL disks are solid.

so which one is better?

arguably, the SE.

Also an easy way to check, would be to see if the rear end has lug studs in it or not. SE used lug nuts instead of lug bolts like the non -se's.

I have to disagree...GSL is better. the SE may have a 4.09/4.10 gear ratio but the teeth are weaker than the 3.90.

hence "arguably" :)

coz I've replaced a few in the past.

i have a GSL rear, and i enjoy it.
the only thing i can complain about is that its at about 4000rpm when i'm on the freeway, but i'm sure others complain about that too. it would only be worse with a SE rear?
Would the drive yoke be different going into the 3rd member on an SE rear? bigger in size maybe.

try driving my RXs with 4.44 and 4.78.

if i didnt drive on the highway so often i'd prolly have those gears too.

I drive them on the freeway, cant go past 85 without big time humming noise

The only difference between 84-85 GSL and SE rearends are the PCD, brakes, and the R&P. I like the 3.9 better (stronger and if I wanted bigger I'd go 4.77), but the SE got bigger brakes. Who cares about PCD you can get wheels in either size. I like the GSL better because it's 4x110 so if someone steals my wheels at least they can't use them.