I used the bolt in and then welded them in also. I do not even remember what I paid but you can do a search at Summit Racing. Mine work great. You need to get your car on a lift with all the cars weight on the wheels. Or you can jack up the rear from the axle until the car lifts at the back and keep the front wheels on the ground. Hope that leaves you enough room to weld if you do it yourself.
Pull the back seat bottom out before you weld. (And pull any carpeting aside also.) The floor gets hot where you are welding the rear end of the subframe connector to the rear subframe. I didn't and the seat got mighty hot.
On the wheels is a must for convertibles that are more prone to flexing. I think home made connectors on my 65FB were welded with wheels in the air, so far I haven't noticed any change in door alignment or similar.