Is there a difference other than the mounting position being different? Never had anything on this except 139 flywheel. Are starter drive tooth pattern same or different pitch? Since I have to make mounting block position is nothing to fix.

I know 139 spins better and faster and not what I am questioning.

A 139 is a Mopar tooth design I believe

It's called a 10 pitch and the teeth are much wider and much harder to just have one bust off

The starter internals will break easier than ripping teeth off the wheel.....from my first hand experience....

A bad kickback usually wrecks a 168 wheel real quick.....the same kick back will twist the starters armature before it rips a tooth off of a 139


Ask me how I know ? LOL

Rotor phasing being even slightly off can do some real bad stuff......crossfire and whamo your nice new starter is semi junk

Mark Payne to the rescue....He probably has not seen anyone else wreck a starter that bad since.....He's a golden guy and always has been !

figure you know same way I do. Experience is hell of teacher isn't it?

I had a 509 started fine never any problem gas or alcohol

Built a new 565 and immediately had vicious kickbacks out of the blue !

Wrecked a ton of stuff and basically found very little other than rotor phasing off not enough you'd think to cause a problem......WRONG....

Never had much trouble after fixing it

Occasional drive issues but easy to fix in a short time...

Starters take a beating.....

with MFI giving me hell getting set. A primer system I am trying to figure out jetting for and amg that is set close but not dead on. A beating is understatment. Throw in a ten yo starter that has been reuilt cpl times and you get the picture and it is not art work.

I ran a Ron's Terminator on the 565 and had the Primer Plus...

Played with various starting setups...

For a while I used some timing retard triggered when Primer plus pump was turned on....off no retard...

After a while I went back to NO retard and very little problems

Eventually back to a gas carb and once in a while on a cold start I'd get a fairly minor kick back but never was enough to hurt anything.

Contrary to what many say I found turning the ignition on right away fired right up.....stay off the gas pedal engine hot.....started up like a Q-Jet cold most of the time

QuickFuel carb.....best working Dominator I ever had and was that way right out of the box......

The 139 tooth stuff is 10/12 pitch, 168 is 12/14 pitch. I know normally pitch is a single number, but that's just what I remember them being called. If you're talking Hitachi style, the 10/12 is the stock gear you'd find in a starter for a 280ZX or a Thermoking Refrigeration unit.

Start Retards are hard on starters.

Rotor Phasing is a huge deal keeping a starter from getting tore up.

can the drives be swapped out? I don't have a 12pitch to compare to the two 10's I have. Looks like I could swap them out if rest of starter is the same. I am finding starters I want but the 10 pitch is out of stock. No reason to buy conversion kit if that is all it is.

I’m not certain but think yes the drives can be swapped.

I wouldn’t buy one without asking someone who could better confirm that

they are swap out. Called HOP and said I could order and swap mine in.Even going to sale me one w/o drive and use cheaper mount since not going to need it. Saved a few bucks there. Got to yank my starter and dbl check drive before ordering.

The 139 tooth uses a 10 pitch gear which is what Mopar uses and it is used in GM diesel applications. It is about 30% bigger gear.

The drive gear on the starter must also be a 10 pitch gear to match. Also the mounting nose block changes slightly to move the pinion toward crank centerline about .050"

All I know is HOP says my drive will work just fine in the starter he builds and no issue. Who am I to argue? Heis sending starter that had std drive and I am installing my drive and using my mounting block.

If Mark says it will work, then it will work.