Recently blew the diff in my gsr transmission,(broke the case aswell) which isn’t the worst as i planned on taking it out soon and putting an ls fith gear in it. I found an ls transmission so im looking to put the gsr gear sets in the ls case using the ls differential and 5th gear of course. I want to keep the gsr final drive aswell just wondering if it will work with the ls differential?

 

I want to say yes the gsr gears will work in the ls transmission. I built an em1 trans with spare parts from two separate b series transmissions a couple years back. Biggest thing to consider is checking the thrust clearance on the input shaft and the differential. Adjust these clearances accordingly with new shims. If its the same clearance as k series then you are looking for .004-.007 of clearance on the input shaft. Differential states .004 but I would like to think it has a couple thou's of room just like the input shaft.

 

This answer is pretty close... as in YES-ish. Let me add a few key details:

The differential "free play" or thrust clearance is between .000" and .004". The important part there is that .000" is actually .000" and not STRETCHING the transmission case because the overall differential assembly is taller than the space between the bearing surfaces.

Moving your LS 5th gear pair over to the GSR main shaft and counter shaft is straight forward. Also, use all three shift forks from the GSR transmission (technically, this is the EASY answer but in fact, you only need to move the GSR 3/4 shift fork over, so pick the best out of the 1/2 and 5/R shift forks between the two transmissions and use them).

Lastly, the GSR counter-shaft has a 4.40 final drive gear at the bottom and your LS differential has a 4.26 final drive gear bolted to it. You cannot bolt the GSR 4.40 ring gear to the LS differential... the opening and bolt spacing is LARGER than that found on the LS differential. The good news is that you can find a suitable 4.40 ring gear from a B16A transmission and it will bolt directly on to your LS differential... thus, keeping the "GSR" final drive ratio of 4.40:1.

 

Can I use a b16a2 ring gear?

 

Absolutely.

 

There are 2 different size of diff for B series trannies:

B16/LS -Smaller
GSR/ITR - Bigger

If you are using LS differential, you would have to use the match LS main/countershaft and move over GSR gear set into it.
Make sure to use the matching main/counter and ring gear with it. Gears are interchangeable.

I personally have very similar tranny as you are currently debating on.
1-4 GSR, 5th LS, ITR LSD diff with larger 4.4 GSR ring gear/main/counter shaft.