They do but you have to do this to your torsion bar crossmember. If I were you, I would do this so I could do a chrysler 500/518 transmission. Is stronger than that GM trans and the 500/518 can be built quite stout, easy enough to handle what you want to throw at it. IIRC that trans will bolt up to your 6.1 hemi without a pricey aftermarket bellhousing adapter because I think those new hemis just use the standard small block bell housing bolt pattern. Normal transmission gear ratios and a .7 overdrive ratio. IMO just want you want for your combo.