Hi Mark, welcome to Outdoorking. So far as getting parts for Victa ride-ons such as the 5-26 is concerned, it is often best to go to the actual manufacturer rather than Victa. AFAIK Victa did not ever make ride-on mowers, but re-badged various existing commercially-available units. However I do not know who actually made the 5-26, or its normal model name or number, so you may need to consult Bruce, the Outdoorking site owner, to track that down.
So far as part numbers for springs are concerned, on that mower Victa's part numbers for all of the specific parts begin with TM, and their numbers for all of the generic parts begin with HA, so I do not understand the number you have quoted. I also do not know which pair of springs you are referring to. There are two springs supporting the front of the mower deck (Items 12 & 32 on Page 12 of the illustrated parts list), and their Victa part number seems to be TM60195A. They are described as "Spring .75 OD x 8.65" Lg". So, if the two springs you are talking about are three quarters of an inch in diameter and 8.65 inches long, this may be them.
