The W58/57/55, can all be fitted to a 1G with a 1G manual bellhousing. These are quite often available on these forums, at a reasonable price. The IS200 Lexus box also "bolts up to a 1G", with other mods to car. Dont know what the weights are but I would expect the 3S-GTE to be a little lighter than the 1G-GTE.