Towing with a TH200-4R

[OldsSW]

I have a GM fullsize wagon with a 7A head 307 Olds and a TH-200-4R (yes, it's a slug). I have been using it to tow my boat around since it makes a good vehicle for fishing trips. The car has a stacked plate 18,000 GVW tranny cooler, in addition to the factory in-rad cooler. The boat and trailer only weight about 1000 lbs.

Is this too much of a load to pull in OD, or should I pull in drive? My TH200-4R doesn't lock-up in third, so there is a big drop in fuel mileage when I use drive. I recently pulled the boat about 100 miles on the highway, and it seemed to pull well in OD having enough power to keep the torque convertor locked. I dropped the tranny down to third before the big hills.

Is this a bad practice, or should I just pay for the extra gas money and tow in third? I haven't torn into a TH200-4R before, so those of you who have done many rebuilds or know these tranny's really well please chime in.

[OldsSW]

Perhaps I should just wire up a lock-up swtich and run it in third?

Is there anyone with any advice? I really don't want to damage my transmission, but with the price of gas these days I also want to be economical.

[77 cruiser]

I'd say you're OK doing like you are. As long as it pulls with the conv. locked you aren't building any excess heat. Also a good idea like you said to wire for 3rd LU if you tow where there are a lot of hills.

My .02 are added

Jim

[OldsSW]

77 cruiser:

thanks for the response, your deductions seem to make sense. Do you have a 77 Custom Cruiser wagon?

Anyone who has an advice, feel free to comment.