Ahhh...ok, thanks for correcting my confusion. Hope this helps others as well. For a stock guy like myself though, the older 180sx diff would be the way to go it would seem. Time to do a little searching.
I was considering the j30 diff just because they seem so plentiful, but as suggest my stock motor set wouldnt benifit from the 3.90 gear set. Except for maybe on long touring/ highway trips.

 

You're not going to notice much of a difference in gas milage with a 4.36. Me and Epstein used pretty much the same amount of gas on a trip to deals gap last year. He had a 4.36 + helical I had a stock 4.08 + helical and I'd always ask how much gas he used and it was with in 1/2 gallon of my car each time. That was about 1500-1700 miles of driving.

 

My guess is that something to do with the final drive in 5th. As it doesnt see the same affect as running up thru the gears 1st thru 4th. 1st gear must be nothing but a blip with the 4.36...its almost skip-able with a stock diff for crying out loud!

 

That wasn't even a question. I know they are going to be different. lol
Your car is going to feel like its on rails, mine is like the rear end is on skis

 

Not really, It helps when you have 245-40-17 tires or bigger, which we both have. So it makes a difference. Stock size wheels tires might be a different story.

I know I really want to get another 4.36 soon.

 

I dont know if its that drastic. Luckily I'll be on a fresh set of tires for the event too, so you'll get the full effect.

 

Dan, I'll take you on the drift course and wont even clutch kick or ebrake just feint and let off and you'll know haha

 

i have a j30 on pretty much stock ka and is'nt unbearable, dont get me wrong i have been looking for a 4.36 gear but no one wants to sell me one. the j30 feels good when you dont want to slide, i can feel it pushing the car though the corner unlike my nismo 1.5 way which put the ass out no matter what. its really hard to break a vlsd, all you have to do to maintain it is to make sure it is'nt leaking and it has plenty of fluid.

 

VLSD's dont break they wear out. The fluid inside the unit itself (not the gear oil) eventually breaks down and cannot be replaced.

 

a friend of mine has a tomei 2 way and that thing kicks hard just daily driving it first through 5 gear you feel it lock up hard core kinda feels like he dumps the clutch everytime but he doesnt..i have a hicas vlsd witch feels the same as a stock open diff while driving but when you want it to kick in add gas you can feel it pretty nice but nothing like the tomei 2 way, and the vlsd you can feel in the turns way better than open diff,and it has the same gear ratio as the stock s13 rear diff