TKX bellhousing offset dowel confusion

Measure them carefully. Most of the mopar dowels are sold as .500" (ford) when they are actually need to be .496ish. This is why most people end up with RobMc dowels.

https://www.robbmcperformance.com/products/dowels.html
For fine tuning I make my own but anything that needs more than a five thou gets the RobMC dowels. If you want to make a set to verify how much offset is needed (or not), the process is relatively easy. If you have a drill press and a long 1/2" bolt you can use a section of the shank to make a set of dowels by chucking up the bolt and removing marerial with emery cloth and measure with a dial caliper to get .497ish. Extra points for drilling and tapping them 1/4-20 for easy removal.

A down and dirty way to find center is using a section of 1/2" shrink tubing to align a chucked up center punch and the dowel which is locked down in the vice. Index everything, lock the table down and swap over to the 13/64 (or #7) drill bit. Once the hole is drilled you can carefully use the chuck to start the tap. Once the tap is eating you can release the chuck and finish with a tap wrench etc.