I need a tech on this rear end I found

that one looks like toast, rust on the gears so they are not usable, you could reuse the sure grip and have it installed in your rear for a couple hundred dollars labor plus the $199 he wants for it plus shipping you are going to be near $500, not worth it in my opinion, a 7 1/4" is stronger with the sure grip in it because when you spin the wheels it will put load on both side gears as it try's to spin both rear wheels, if you are not prone to do burn outs and spin the rear wheels often, a standard open rear works better in a normal driven car, you are most likely to spin the wheels on wet rainy days when traction is poor, this happens most often when going around a turn, with a sure grip, posi, locker, or other type of limited slip or locking rear you will spin both rear wheels hydroplane loosing traction and causing the back of the car to spin around causing a complete loss of control, where as with an open rear in the same situation only one wheel will spin leaving the other side in contact with the road preventing the car from spinning out of control, not saying sure grip's are bad just that the have there good and bad property's and you need to be aware of them when driving with one