73 Dart 360 Transmission Options?

[mario03srt]

All,

My car is up and running pretty well. The 727 runs ok but I want it gone through and beefed up with a TG 2 kit etc. Before I go into all of the expense from a Tranny Shop I thought that I would explore my options.

What other auto Mopar transmission(s) will go into my Dart/360? Looking for a OD style to get my revs down from 3k @ 70 mph if possible. I have a 3000 stall B&M Holeshot and flexplate and 425 ponies and a 3.55 gear. I have maybe a 1500.00 budget but that's not super firm depending on the swap.

Thanks,
Marion

 

[Chained_360]

If you wanna stick Mopar, the A518 is basically a 727 with an overdrive unit attached, and the A500 is a 904 with an OD. Both of those tranny's require some cutting and reinforcing of the transmission tunnel to fit the bulky OD tail of the transmission. These can be found in Dakota's and trucks, but try to get one built before '96 (that's when they switched from hydraulic control to electronic). Some have lockup converters and some don't, I can't recall how to identify the lockup ones.

 

[mario03srt]

So will a GM unit fit?

 

[xLURKxDOGx]

So will a GM unit fit?

Yeah, it’ll fit a 350........

Jake

 

[Chained_360]

You can get adapters for a 200r4, but I'm not sure how budget-oriented that option is. Custom driveshaft, shifter, mount, bellhousing/flexplate, etc.

You can get an A500/A518 from local pick n' pulls or wrecked vehicles for fairly cheap. Has a mopar bolt pattern, takes a mopar flexplate, you just need a custom tranny crossmember and some tunnel mods. If you look for used units, the A500 is also called a 42RH and the A518 is called a 46RH. Make sure whatever unit you find ends with an RH, not RE. H stands for hydraulic control and E stands for electronic control. Pretty much any 90's dodge truck or van with a V8 should have one.

 

[KickDown]

If you go with an A500 or an A518 you will also need the lock-up Converter.

 

[Clelan]

Right now, I am in the process of installing an A-500 in my 74 Duster behind my 360. It is replacing as A-998 that had issues. It is bolted to the motor and I am in the process of modifying the trans cross member. It bolts up really nice. The tunnel mods are nothing to be scared of. I think the A-518 fits the tunnel section about the same as the A-500 but I am not entirely sure.

It is a simple straight forward swap that has been done lots and I am counting on the gains being significant, though I have not driven it yet. If you think OD is in your future, find a JY 95 or older trans and rebuild it instead of the one you have. It allows the use of that deep rear gear set we all want while retaining the ability to run on the highway at 80mph.

Cley

 

[mario03srt]

Cley/All,

How bad does the tunnel need to be modified? Can that be done with the engine in the car? Are we talking some cutting or bashing in a area?

Marion

 

[Chained_360]

Cley/All,

How bad does the tunnel need to be modified? Can that be done with the engine in the car? Are we talking some cutting or bashing in a area?

Marion

It's not that bad, the transmissions are largely the same shape except for the OD ones are a bit bigger in the rear due to the extra set of gears. From what I've seen you just have to cut the reinforcement bar from the tunnel of the floor pan and make it thinner by welding a thicker plate directly to the floor. I'll dig around for the thread on here real quick.
Edit: here's the A500 swap thread I read when I was researching it to see what it took: 42RH / A-500 in a Duster with pictures.

 

[Clelan]

Unfortunately I don't have any photos of the mods to my car. I did not actually do the tunnel mod myself, it was done when I bought the car body. Here is a picture from the build thread by the previous owner. Basically, you need to cut as much of the original cross member as you can tight to the floor pan (crappy red line on photo) and weld in a flat plate to replace the part you removed. This shows it with the floor removed but that would not be necessary. You could do it from underneath if you removed the carpet. I will be modifying the removable section of the cross member this weekend and I'll try and take pics of that.

Cley

 

[mario03srt]

Awesome Guys. I'm going over to Extreme Automatics here in town and get their take.

Marion

 

[Clelan]

Here are a couple pics I took from under my car this weekend. Kinda shows the tunnel mods from underneath with the trans in. The trans is not pushed up into the tunnel in these photos. The cross member needs to be sliced and have the center dropped about 3". I modified my factory one for now but I am going to build a complete new one in the future because I'm picky like that.

Cley