Yes they did but the 3.9l used the same bell housing pattern as the V8. Remember it's a V engine, unlike a slant which is a L engine. A slant 6 bellhousing pattern is totally different.
There's only 2 ways I can think of using a 4 spd. overdrive A500 on a slant 6 and that's to have the bellhousing cut off the A500 and a custom slant 6 bellhousing installed. Or make an adapter similar to the cast iron one showed in the picture above.