Coupler aftermarket replacements?

Hi Gang,

I just got done replacing my arms and manual box in my 66 cuda. I ordered a Coupler rebuild kit on Ebay for $12 and will be doing that next. Anyone know of aftermarket manual box-couplers that work? Seems like such an easy joint I don't know why Chrysler went with this elaborate box type coupler. Then again, I'm no engineer either :)

Thanks in advance,

Bill