REAR DRIVESHAFT VIBRATION

I recently lifted my 1991 chevrolet blazer and have since noticed a considerable vibration around 50 mph and higher. I have seen expensive driveshafts which claim to cure the problem but judging by the pictures and descriptions the only modification to the original design is a H type double caran joint at the front of the shaft behind the slip yoke. what i need to know is Can i simply add a h yoke to my existing driveshaft and achieve the same results. also there is the issue of 3 different styles in

2 different designs. these are 1310 1330 and 1350 in either normal or high pinion angle. as i said it is a 1991 chevrolet blazer k5 with 10 bolt frt and rear and a np 241c transfer case. thanks for the assistance. mojo