Altec "A" vs "B" series xfrms: VDC+ values??

[Analok]

Okay, so I've been tinkering around with various Altec transformers & building converter plugs to mate them to an Ampex AG600 series pre. I'm wondering if I'm making too much work for myself by building a converter for the Altec "A" series (rated +12WVDC) as well as one for the "B" series (rated +12 to +20WVDC). Take for example an Altec 1588A vs. an Altec 1588B: The pinouts are the same, but do they use the same transistors et al, thus both being suitable at, let's say a nominal +18VDC (the Ampex puts out +24VDC and so must be reduced in any regard)? Was it just a 'less conservative' label change between the two cat.no.s or are there physical changes component wise? Not much out there schematic-wise other than the labels themselves, and I'm not about to peel the cans open to find out, so.....

TIA Slutz