Need new ratio SM465 86 GMC Pickup

I have a 1986 GMC 454 2WD 3/4 pickup truckQuestion:  I have gmc truck 2wd and has GM SM 465 transmission 4 Manuel speed The factory gear ratios are 1st : 6.55 2nd : 3.85 3ed : 1.70 4th : 1.00 Reverse : 6.:09 I would like to upgrade the ratios without any change in the main transmission body just need to change the rings inside the transmission The ratios that I would like to have are 1st : 3.27 2nd : 1.97 3ed : 1.34 4th : 1.00 Reverse : 6.:09 So the changes will be only in 1st , 2nd and 3ed Please note that the tire height is 33 inch The rpm up to 6200 rpm The rear end ratio 3.73 I need help on that.Answer: Sorry there aren’t any ratio changes available for the SM465.   You will need to change the rear end ring and pinion your currently have 3.73 we suggest you lower the ratio to 4.56 this will drop RPM on the free way.  You can see the parts we can provide for the SM465 on our site.