Correct me if I am wrong, but the A500 is 904 based and the A518 is 727 based, correct?

Do both transmissions share the same bellhousing bolt pattern?

Is the starter mounting location different between the two? If so, how much?

If my first statement is correct, does the 518 have similar parasitic losses to a 727 and a 500 to a 904?

Reason I ask:

AndyF at AREngineering has been working on an adapter plate for me so I can mount an A518OD behind the slant in my truck. I originally decided to go with the 518 because my truck will still see some towing every once in a while, as well as some load hauling, and I wanted the "stronger" trans.

However, as spring is setting in, and my mind has had way too much time to think (read...boredom), I began thinking about parasitic losses, and if an A500 has appreciably less parasitic loss, I may be better off. Being able to use either would also open up my options when it is time to buy a core.

Either way, the trans will be getting a full manual reverse pattern valve body, if it matters.

-Aaron

You are correct; 500 = 904, 518 = 727. The pans are even the same shape as their parent trans, so they are easy to tell apart. Both use the small block bolt pattern, so you can take your pick. They will both sap more power than their 3-spd versions, but the 500 should be less than the 518, as you guessed. Most of the trouble with these trans is with the OD assembly burning up the reverse clutches, but there are fixes available in the aftermarket if you're going into it anyway. I've heard that the trick is to stay in 3rd when hauling a heavy load with a stock trans. I think a well built 500 should keep up with a slant, no problem. Don't forget they use the wide ratio lower gears, like a 999.

Hang on a minute...

Will an A500 bolt right in to my Dart? Should I consider doing this? If so, how can I tighten up that OD/reverse clutch problem so it doesnt fall apart?

You said the 500 saps more power than the 904, are you saying you lose power with this transmission? If it has a wider gear spread (lower first gear, OD gear), wouldnt it hook your car up better?

Would an A999 be a better choice for me? Is it also less efficient than the 904?

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I've been calling it as i see it for my entire life and that's not about to change. Take it or leave it.

The 904 case can take the A-998/999 guts (same family), the A-500/518 has an LA bell housing so you have to get one of mopar's 'cheater' peices from a 60's truck/van (they didn't have slant six A-727's then so they made a slant six to LA adapter...), with the adaptor you can use pretty much anything that bolts to a 273,318,340,360, 5.2M,5.9M (I hear also 3.9M..etc...). The coouple of problems to over come are finding the adaptor, refabricating your tranny crossmember and tunnel to take the A-500/518, and making sure you get one of the early non-electronic units (like 1989-1992)...

-D.Idiot

Super 6 has a big tunnel in his truck, so he's got the room for a 500/518. Like DI says, A-bodies have a much smaller tunnel and the tranny crossmember is part of the torsion bar mount, so it's major surgery to get one in. I'd stick with the 3-spd.
It takes hp to work any auto trans, but some aren't as hungry as others. In fact, the 904 family is one of the best, right down there with a PG in terms of power loss.
Wide gear ratios make the engine work over a wider rpm range, so there are trade-offs. A lower first gear will launch you harder, but you might fall below your cam's bottom end when it shifts. It has to be part of a whole package to work well.

When I had my 88 D-100 my 904 lost 3rd gear so I swapped in a 518. To do it right, you need the trans x member from a 89-93 OD equipped truck. The OD units are identical between the 500 and the 518, the only difference is that the diesel version had an extra clutch plate in it versus a gas motor one, and yes you can put a diesel OD unit on a gas engine trans. Basically the OD is all enclosed in the tailshaft but no you can't just bolt a 500/518 OD unit onto a 727 or a 904.

Thanks for the info everyone. I know I need an adapter plate, AndyF should have me set in that department in a few weeks. Last I checked, he had the adapter plate done, but still needed to machine the crank bushing.

I haven't decided whether the trans swap will be a summer or next winter project. Right now it is looking like next winter, simply because I will be out of town for the majority of the summer. But I can still dream

About the trans tunnel, I fully expect to be doing some shett metal work. My truck doesn't have the huge tranny tunnel the 4x4's had, and the 904 is a pretty snug fit, but the garage now contains an acetylene torch and a welder....so let the fun begin.

Now I just need to get my serpentine belt conversion finished, and I can move on to more important things.....like overdrive!!

-S/6

The starter location is slightly different between the 904 and 727 and so is the shape at the bottom of the bellhousing. The adapter plates that I'm now starting to make will work with either tranny but the inspection plate and the starter shield are unique for 904 vs. 727. But I'll probably just throw in both styles with every kit rather than try to worry about which goes with which.

You need a /6 flex plate since the /6 crank pattern is slightly different than the SB crank but I assume that a /6 flex plate mates with the OD tranny torque convertor. At least Lou figured out how to do it. (maybe oval one hole on the OD flex plate?)

Andy, I have been going to your web site, since I first heard about you building the adapter, but haven't seen anything there. Are the adapters available yet? What kind of price? Don't need one yet, but am trying to plan a future project.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

The stock Slant flexplate will bolt right up to the OD/lockup converter. I actually used a V8 flex plate with the one offset crank hole drilled using a stock Slant flexplate as a guide.

OD rules...

Lou

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Home of Slant6-powered fun machines since 1988

Charlie - nothing is on the website yet but the first batch of production adapters is scheduled into the machine shop. I usually build parts and have them in stock before I put them up for sale on the website. I know that is opposite of what Mopar Performance does but I've alway been a bit of a rebel!

Price isn't firm yet but will be around $400 for the complete kit of adapter, crank spacer and both shields.

Never had anything with a lockup convertor before...What controls the lockup?

Will I need to wire in a button on the shifter handle and disengage it while decellerating, or is there something I can do so it handles itself?

As for the trans tunnel, Pops got a welder, so I'll just drive it over there. He's a good welder, and I'm good at hacking holes in stuff.

I'll be using an A-500 with a Weber DGV 32-36 unless someone can tell me otherwise.

What are the good aftermarket sites for A-500 mods?

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"When applied at precisely the right time, Ignorance is a powerful tool, usually even surpassing knowledge" E.J. "Michigan Madman" Potter.