Thats strange i had two replacement clusters for my E32 735i one blue and the other cream. One was from an IL but they both worked, only the IL had a different fuel gauge, The mileage remained that of the car. You possibly don't have the dreaded capacitor problem do you? From memory there are about 5 220uf capacitors that required replacement to rectify a common cluster fault on the E32, if you do a search on cluster repair you should find a step by step guide identifying the components to replace. I can't remember the exact symptoms as it's a while since i sold my E32 but is probably worth a try..
I think i still have the spare clusters and code plug someware but there probably not much good to you as i'm in Australia.