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A500 IN A 72 B-BODY


Well-Known Member
Local time
3:28 PM
Jul 30, 2013
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South Bend, IN

I have a 72 Plymouth Satellite, 3300 lbs dry weight. The current 727 is smoked due to blocked cooler but still functional. With the current set-up, 360 with around 350 HP/400 ft/lbs, and 2.94 gears the car does well but would like to change due to cruising and acceleration.

I now have in hand an A500 from a 1990 Dakota. Although it has a recent rebuild, I would like to used it as a base for an overdrive swap. (The car is not drag raced, just a nice cruiser.)

What rebuild upgrades would you recommend?

Other information:
Not used for towing.
OD will be tied into my cruise control.
Lockup would be nice but not required. It is currently a 3 pin.
The rear mount will be fabricated by myself along with tunnel modifications (if required).
Looking to upgrade the rear end to 3.73.
Wiring for OD and Lock up will be pressure regulated.
Kick down will be tied to carb by cable linkage on a 1:1.

The information above, broken down to RPM, shows the engine speed with a 3.73 with a shift of 40 for 1-2, 70 for 2-3, and 110 max for 3rd. Maintaining a 5000 max shift point. Cruising speed around 65, just over 2000 RPM,
Basically, if its a decent rebuild I say run it as is -

I am doing a 46RH swap in my 73 Challenger - basically using the stock torque converter, doing the required wiring, and then just doing the minimum to get it in and running - running the 73 kickdown set up and working with the factory slap stick -
Cleaned it up yesterday. I am adding a stage 2 shift correction kit, 3/8 lines, extra trans cooler, replacing seals on input and output, and also running factory slap stick. Will have around $700 bucks in it, start to finish.
Three weeks ago, the 727 took its last breath. Gonna rebuild it but went to the task of adding the A500.

No floor pan changes but some mods required.
  1. Had to grind away the manufacturing tabs on both sides of the overdrive unit.
  2. Fabricated the rear trans mount and used a 92 cheby transmission mount. (a lot of material came off the 72 mount but gusseted for little more support. Speedo clearance was finished under the car. )
  3. Used a Lokar downshift cable with a fabricated bracket.
  4. Used the PATC overdrive controls. (Basically pressure switches plumbed into the 3rd gear servo pressure port. Had to use a 1/8 street elbow with a 4" extension to run forward to gain room for the switches. Wired to a adjustable vacuum switch to downshift from overdrive if intake vacuum drops below 10 hg)
  5. Fabricated a lower bracket for the console shift mount at the transmission. (no binding in the shifter but the overdrive housing changes the angle from 90 to about 95 degrees.)
  6. Ran 3/8 aluminum line, with 6AN fittings to the tranny cooler. Ran to the passenger side due to headers being so close.
  7. Shortened the drive shaft using a local shop by 1-1/2". (Added new spicer u-joints, not required but since they had to remove them anyway.)
  8. Running a new tranny cooler with fan switching on a controlled 175 degrees.
Ran it through gears while still on stands today. Looks like the speedo gear will have to be changed but will verify during road tests. Will be road testing over the next few weeks.
hows your progress coming along?
im wondering what parts/numbers you bought and esp where and how much grinding you did?
are you happy with the results?

i have one im doing myself,same combo 3:73 gears.
hows your progress coming along?
im wondering what parts/numbers you bought and esp where and how much grinding you did?
are you happy with the results?

Have taken the car out for some road tests. Shifts well and enters OD cleanly. I have not changed out the rear gears yet so don't have a full review of how good it can get. Will be out at the shop later this week so I will snap a few pics of the ground areas. The main body of the trans will need nothing. Only the overdrive will lose material.
Did not have to hammer or grind on the floor pan or cross mount.
The trans mount from the chevy will need the holes elongated slightly, 1/8 inch per side. (will provide part number from Advance Auto Parts <$15) The plate welded to the modified original mount will need to be a Z bar with 1-1/2 inch offset. Can take pictures of that as well. Will help where I can.
Worked as intended. Buy the 50mph, 52mph option. With the bumped up line pressure, shifts at 45/48mph. I have yet to tune in the vacuum switch to my application. Cost me $135 for the driveshaft. The fittings and line came from Summit Racing. Jegs provided a fan cooled auxiliary cooler and temp switch. I will provide the PN(s) in a later post. Receipts are with the car.
I feel bad that I did not close out this story.
Finished the install in 2019. Added 3.91 position gears last year. Awesome cruiser now and good mileage. Ran 1800 miles on a drag and drive adventure with great success.
2500 rpm at 75 is nice and acceleration is such a change from 2.91 gears.
A500 with upgrades is just fine behind 5.2.
Nice job. Planning the same swap from 904 to A500 on my magnum 360. Adding 3.91's from 3.55. Couple of questions....Did you replace the torque converter? Are you using lock-up? Where did you get that chart in post 2?
The chart is one that I made up. Pretty good at excel so built the formulas and started playing with possibilities. Rpm changes with change of gear, tire sizes. Helped me find my happy points.
On my last post, it says “positive” rear gears. Should be “posi” or limited slip.
Using the lock up tied to my cruise. Don’t like it engaged under 50.
As far as mpg, if you care, is 18 mpg on long cruise at 75 mph.
Have run over 3000 miles this year. Love having the overdrive. Now on to the A/C.