I've actually just finished installing the bolt-in design (to the trans cross member)... purchased from Mancini... into my Challenger. There are two different designs... the first design has the DS loop as a 1-piece round circle; the later design has the DS loop as a 2-piece 8-flat sided bolt together design (supposed to be a better design for convenience in assembly and dis-assembly with the top hole of the loop being bolted to the floor (drilling the hole into the floor is required... if so desired).
The steel is 1/4" thick everywhere. I weighed the assembly and its at 10 pounds (with all the bolts/nuts).
The assembly takes a little time for adjusting the fitment... took me one evening.... determining the variable overall assembled length, as well as the assembly of top or bottom plate mountings, and the included spacer shim if needed.
The unit is approved by NHRA for racing, per literature and Mancini's advertisement.
The only problem with the piece is that the front plate that attaches to the trans cross member will need a clearance v-cut for the S-hook of the emergency cable. The front main unit could have been made at about 1/4"-3/8" less in height... it hangs a bit lower than the crossmember. As I made v-cut in the center, the S-hook will now clear.
Note: I actually have an extra same unit (later 2-piece loop), still brand new... willing to sell... PM to me if interested.