Jeff will install the T nuts, and so far has been doing it on a case-by-case basis using the customer's specified mounting pattern. I'm encouraging him to adopt the pattern that Phil got as standard, which fits the 3 1/2" and 4" Guitel casters that are found on many pro audio mfgrs. cabinets and cases. The wheels on Phil's sub are 3 1/2" Guitel like the LA400 uses.