kmj,
I don't know of any other current manufacturers, but, If you watch the auctions, there are some really nice H&R convertibles that come up for sale regularly.
A few different models, mostly model 676, and 686.
676, casecolored, sa/da, windage adj rear sight, fixed front.
686, same as 676, except has fully adj rear sights, and target style ramp front sight.
Model 649 same as 676 except blued.
Model 650 same as 649 except nickel plated.
All have single action style loading / unloading.
Well built, good shooters.
They haven't been made for quite some time, but, you can still find some really nice ones at reasonable prices.
Here's a few pics.
Model 686 4.5" 1980
Model 686 5.5" 1980
Model 686 7.5" 1980
Model 686 10" 1982
Model 686 12" 1980
Model 649 5.5" 1980
Model 649 7.5" 1980
Model 650 5.5" 1980