ive got an 86 sammy with a spoa with 31s  looking to do some gear work,  should i do t-case and front and rear gears,, rocky road has a combo deal,,  4.1 t-case with 4,57 front and rear r&ps  for 1060$.. i spend alot of time in the so cal dez, do some crawling at  truckhaven but also hit up glamis from time to time. i heard the 6.1 t-case i way to low for any sand.... so what do u think

If you are only going to run 31" tires, there is no need to change the r&p gears.  Go with a 4:1 t-case or something lower.  That will be all the gear reduction you need.

so u think the  4.1 should be enough. it wont put to much stress on the rest of the drivetrain.by adding the 4.1t case does it lower your over all gear ratio .it says like 18% lower in high,is that 2wd high . And 84% in low . If that's the case then I'll go with that and add a locker and so stronger axles

The 4:1 case reduces 12% in the high range and is spot on for 30" tires.  So with 31" tires you will still be a little off, but it's not too bad. 

FYI, I have a Samurai with this same exact setup and it does well and I've never had a problem with the 4:1 t-case.  10+ years and counting.

Do u think the 4.9 tcase would be to low  for sand..or will that be better for 31s

I have run with several Zuki's with 4.8:1 and 31" tires, they do pretty well for themselves.  With sand you are going to run into an issue with not having enough power in the soft stuff.  Nothing you can do about that other then get a bigger engine.

Do u think the 4.9 tcase would be to low  for sand.. or will that be better for 31s

Do you need to maintain your highway speed?
31's are about 17% oversize and the 4.89:1 Transfer-case gearset offers 16/18% high-range reduction -- a good match.  Another factor to consider is that early (pre-'88.5 or so) Zuks had a too-tall 5th gear which was reduced by 8-9% in later models in order to pull better on the highway, at the expense of a few hundred RPM.     Early Zuks are commonly "over-geared" a bit to get the overall gearing in 5th to work out right for the highway.  If you never drive over 50mph it probably doesn't matter.   

Don't really care to go fast on the road,I took it to glamis last year and it did better than expected. So. I think the GRS  2 from Petroworks  will work just fine with a locker In the rear .. I don't want to get to crazy..what do u guys think about those Goodyear wrangler m/t with Kevlar ..are they worth the money..thank you guys for the help