I did the same and the only thing Raymond offers is walk behind straddle stacker. That seems a bit strange as Raymond first entry into the narrow aisle products was a stand-up rider straddle unit. I know the market is very small (less than 100 units sold in a year) for these type units so they probably stopped offering it or only offer it as a "special" non price book version.
But this might help Clark still offers a stand-up straddle unit Clark model NSR 22 & 25 (4500 & 5000 lb lift capacity).