hello peoples. In my research on ebay I have found that some headers are listed as 2wd only while some are 2wd and 4wd. Whats the deal? also some people list that their part as like 70 something to 86 and 88 to 90 something. leaving out 87 altogether which is the year of my truck!! and others up to 87. but what is clear is something changed in 88 so that things will not interchange. (am I makeing any sense) anyway does anyone know what changed or happened or what?? any info or opinons great.