If you are speaking about the type on Fry pumps, I use clear silicon once they are placed correctly? DAP makes a latex caulk that vends white and dries clear. Easier to see and work that way. Water soluible for ease in clean up. Paul www.severngaspumps.com
If you have any problems using adhesive to hold the gallon markers to the rods, I used a small O-ring (instead of adhesive) to hold the stainless gallon markers to the rods on my Fry 17, after bending the tabs around a used rod. The only O-ring I could find that fit the rods snugly was a metric diameter one.