| Model | Tank Dimensions | Gross Capacity | ||
| Diameter | Height | Litres | Gallon | |
| GT10 | 2.67m | 2.18m | 12,200 | 2,600 |
| GT20 | 3.34m | 2.18m | 19,100 | 4,200 |
| GT30 | 4.01m | 2.18m | 27,542 | 6,053 |
| GT40 | 4.68m | 2.18m | 37,574 | 8,258 |
| GT50 | 5.35m | 2.18m | 48,963 | 10,761 |
| GT60 | 6.02m | 2.18 | 62,111 | 13,651 |
| GT80 | 6.69m | 2.18m | 76,504 | 16,814 |
| GT90 | 7.35m | 2.18m | 92,570 | 20,345 |
| GT110 | 8.02m | 2.18m | 110,116 | 24,212 |
| GT130 | 8.69m | 2.18m | 129,292 | 28,416 |
| GT150 | 9.36m | 2.18m | 149,948 | 32,956 |
| GT170 | 10.03m | 2.18m | 172,134 | 37,832 |
| GT200 | 10.70m | 2.18m | 195,851 | 43,044 |
| GT220 | 11.36m | 2.18m | 221,604 | 48,704 |
| GT250 | 12.03m | 2.18m | 247,874 | 54,478 |
| GT280 | 12.70m | 2.18m | 276,180 | 60,751 |
| GTi 291 | 10.70m | 3.23m | 290,632 | 63,876 |
| GTi 328 | 11.36m | 3.23m | 328,096 | 72,109 |
| GTi 368 | 12.03m | 3.23m | 367,831 | 80,784 |
| GTi 410 | 12.70m | 3.23m | 409,860 | 90,157 |
| GTi 454 | 13.37m | 3.23m | 454,112 | 99,891 |
| GTi 501 | 14.04m | 3.23m | 500,065 | 109,999 |