gear shifter

My 2005 Wrangler decided that enough was enough, and the inadequately designed plastic part inside the gear shift finally broke. So my interweb search started; down one rabbit hole and up another. Pulling the T-Handle off the gear shift shows me the top of the plastic part, and was removed...

I know this isn't exactly a straight-forward answer, there's a lot that goes into it. So, I'll start with the basics and you guys can give me feedback and I can fill in the gaps on anything I didn't specify initially. My Magnum V8 swap is nearing an end. The past 2 days have been spent...