Bohli is what I was going to mention too. If the preceding message didn't
indicate, it is Swiss made. I think they have a website. I've heard very good
things about them and they're not all that exepensive since you can avoid the
cost of installing a TE probe.

Another item to consider would be an old era Ball vario. Some of them were
also internally compensated.

If you're merely trying to avoid the expense and trouble of fin mounting a TE
probe on an older ship, consider a fuselage mounted upright probe as used on
ASK-21s. They work just fine - especially if this would be for an older ship.