Note: This is a 6.3 volute. If you need a 6.1 volute, you will need to replace the entire pump. See AquaFlo XP2e 56 frame Spa Pumps 56 frame spa wet ends can have one of two designations - 6.1 or 6.3. The difference is the measurement between the top two thru-bolts. 6.1 wet ends measure 4" and 6.3 wet ends measure 4-1/8". See diagram below.