WG 4900 vs 5500 differences please help to identify

[GMZombie]

ok i have 2 wg board series either 4900 or 5500 and i know i marked one but its been so long ago i dont trust myself..lol anyways what are the differences between the 2 chassis? i noticed on my 2 they both have the upper left extra pcb on the metal wall. my vertical position control has an extra pcb there on both as well? there is the chassis info on the right side but they both say the same thing evv-20451 main dbq-3 2950013296..im so confused i guess that is what i get for not labeling them better before i moved..

i think i figured this out that the flyback numbers are both the same and they are 53x0531-001 which should be the 5515 chassis..thought i only had one but i guess i have 2 as the 19 flyback is a different number all together.