1970-W30

For you guys that had been following my earlier thread about keeping my new 200-4r cool, this is what cured the problem. After a week or so with an auxilery cooler installed, the 200-4r is no longer running hot anymore. I hooked up a Flex-A-Lite 4126 cooler, it's about 10" x 20" in size, big enough to do the job but not so big that it would be hard to install. It came with 1/2" spacer blocks and push rods for mounting and all but two fittings that I had to buy.
The factory cooler lines are 5/16" and the outside cooler 3/8" so I bought a 5/16" compression fitting on one end and 1/4" pipe thread on the other end for the 3/8" hose barb. Pretty simple installation. Been having 100+ temps lately, trans stays around 180 or so. So, if your thinking of upgrading to a 200-4r transmission, you might as well budget for a decent auxillary cooler also.

oldcutlass

Did you plumb it through the radiator also?

1970-W30

Yes, first the radiator then thru the cooler.

joe_padavano

The 200-4R is very susceptible to heat and the stock cooler is woefully inadequate. You made a good choice for trans longevity. For my Custom Cruiser I snagged the factory aux trans cooler and lines from a similar Caddy Fleetwood.