I won't waste my money on any girdle, I would and do replace the main caps with better aluminum or ductile iron units My reasoning is that the Mopar wedge and 426 Hemi blocks have a very strong design with the oil pan rails below the crankshaft centerline with the renforcing ribs from the main caps so the entire bottom end is supporting the main webbing That being said the RB and 361 and 383 main webbings are thinner between the bottom of the cylinders down to the upper main support so reinforcing the main webbing with a girdle bolted to the main studs and oil pan bolt holes does nothing to add support where it is really needed. The girdles do provide some stability front to rear but no real support to the main webbing The 400 blocks have a lot thicker main webbing stock from Mopar so maybe that is a option if you want to really turn up the wick Your best bet to prevent failure on the main webbing and getting a better block is a new 4 bolt main replacement block If you can find one Be safe don't run over your crankshaft