The gear splitting function of a Gear Vendors is only really usable if you also buy the controller that does it for you, and even then there's really no good reason to need splitting.
I'm sure you can imagine trying to on/off the GV button while manually shifting.
It's not reasonable to do.
Another thing is that I helped a friend install a GV in his 71 Swinger/904 and we had to cut his floor hump and raise it about 2 inches where the GV unit was going to live.
We also had to re design his exhaust piping because it was in the way.
Then there's the driveshaft shortening involved.
Personally I think the 42RH overdrive trans is a much better option unless you are pushing 400hp or more with that 318.:D.
The 42RH is a 904 with a .67:1 overdrive and converter lockup.
It fits with fairly minor mods to the trans crossmember and bolts right up to the Mopar small block.
Did my Dart with one for about 400 dollars by pulling it out of a 95 2 wheel drive Dakota at the pick a part yard, and that included the automatic shifting for OD and lockup.
When I had the 2.73 gears in the back I ran 2,100 RPM at 80mph and got 25 mpg all day long on the hiway.
Some prefer the GM 2004R trans, but they need to be upgraded internally and need an adapter plate to the Mopar motor.
Some things to consider for you.
View attachment 1715492577
View attachment 1715492578