I think you're looking across the fence and expecting the grass to really be the color you think it is. You should have the current transmission properly diagnosed before making a decision. There are few 123 or 126 cars selling for a reasonable price that have everything working and most of the major systems in top shape. "Top Shape" = recently refurbished and expected to be reliable with only maintenance needed in the near future.

IF your current car is in good shape except the trans, you could buy a a remanned and swap it in. The other option is to spend time shopping, buying something only to find that it too has issues that need to be dealt with. Old cars have problems because......they're old.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.