Yes there is different versions. For example the GN 86-87 used a brf valve body some have the Kc valve body some have BQ and so on and so forth. The case is essentialy the same but the internals differ valve bodies govenors etc. The brf is suppost to be the most desired but i not 100% on that.
81 Cutlass Cruiser Wagon; 406 SBC, 12:1 comp, Hbeam rods,forged crank, Comp Solid roller 4/7 swap 673/672 lift, Victor Jr, AFR 220 heads, Comp roller rockers, custom built 945 hp carb,Trans Specialties Th350 Ultra bell and transbrake with ATI 8" 4000 stall, 8.5 10bolt 4.10 gears, moser full lightweight spool,33 spline moser axles, C-Clip elim,moser rear girdle, SSM Suspension, Drag Bag. Roll cage. Best to date 11.18@117
86 GN Stock motor,PTE 6262E, 60lb inj.,TT Chip, Mease 3" Dp, Mease modified stretched Duttneck intercooler,Art Carr 9" 3K stall N/L ,Razor Alky,scanmaster,RJC power plate,autometer gauges,casper knock gauge,Adj press reg, k@n, Lt1 maf + translater.Pypes exh, SSM suspension, Drag Bag.Best et to date 12.58@106 leaving on no boost and a trans that slips bad on 2/3 shift.
84 Cutlass Supreme. 355 sbc, Bowtie angle plug heads 9.7:1 compression, harland sharp roller rockers, comp cam , Victor Jr intake, 700 dbl pumper holley, 4spd Super T10