All RAM, regardless of type MUST pass 5 loops of a full, long memory test appropriate to its age in a motherboard appropriate to its type without a single error.
Modules intended to be installed in groups (30 pin x 4 or 72 pin x 2), if bought in groups, will be, as much as possible, exact duplicate and, where not possible, will be functionally identical.
Some motherboards will take ANY 32 pin SIMM (3 or 9 chip), however, some will take only one or the other, just as some will take 72 pin SIMMs in single or double sided while other may take single only. It is up to the purchaser to determine the chip count or 'sidedness' their board will accept.
In cases of the purchase of a single module to complete a set, we will need to know the characteristics of the module being matched to advise you which module you should purchase.