20# cylinder
Full (80%) 4.7 gallon
(E/F weight) 18#/38#
18"/H------12.5"/D
30# cylinder
FULL (80%) 7.1 gallon
(E/F weight) 24#/54#
24"/H-------12.5"/D
40# cylinder
FULL (80%) 9.4 gallon
(E/F weight) 29#/70#
29"/H-------12.5"/D
If they actually put 8.8 gallons in then you have 40# cylinders (which must have been an optional upgrade for your TT)
Really hard to put much more then 7.5 gallons in 30# unless bleeder valve was left open and propane was spewing out to atmosphere (really tough with 20#)
How tall are yours?
As for pigtail hose rupturing.........3 yrs. old??? Was hose rubbing on bracket/collar/Cylinder?