This truck has 4.10's and a 318. It's no rocket sled, but it gets around surprising well in stop and go traffic. I bolt from stop lights and leave most cars behind. Not in a race, but it goes quicker than the average commuter chooses to. But it sure is screaming on the freeway at 75.

With the 4.10 gear the 518 will be fine, you don't need the 2.74 first gear in the 500. You may need a later style crossmember or modify yours. The tail shaft housing is wider than the 727. You will need to shorten the drive shaft and you will also need a 3/8" cooler and lines. The 5/16" lines and stock cooler will not provide enough fluid volume to lube the intermediate shaft and O/D unit. I would make sure you get and use a lock up converter. It's worth about 300-400 rpm reduction.

Transmission lines have to be upgraded like said.
Driveshaft needs to be shortened.

I daily drive my '73 Dart with a 318 and an A518 with 3.55 gears.
Overdrive is engaged with a simple switch on the console.
Same could be done for a Lockup-version (which I had in the car before). Or use a 3 step-switch.

I used to let the trans shift itself 1st-2nd-3rd, then flip the switch for OD, then again for Lockup.
Can't get any closer to a 5-speed with this.



Not all 518s have OD + Lockup. Some only have Overdrive.

One time the OD stopped working.
A simple replacement of the solenoid inside the transmission fixed that.

My 2001 Ram1500 Off-Road package truck has factory 4.10 gears and an OD automatic.It has tall 275/7017 tires which is why the 4.10 ratio was used,at 70 mph it is around 2100-2200 rpm.I'm sure your truck is closer to 3000 rpm at that mph or slower even with no OD.It will make your truck bearable at highway speeds for sure!
RT

This moparts thread about vibration has me wondering if I put a converter from a 360 on my 318, will it shake?

It will.

The weight is just spot welded on so some careful hammer and chisel work solves the problem.

Kevin