I would never take out a 8 inch for a 8.8,The 8 inch will take more a beating plus you already got it.
HAHA...and what experience to you pull this from?
the 8" is a glass house waiting to explode.
I've had friends with the stock 28 spline axles 8.8 with 4.10's and 350 to the wheels launch on drag slicks for close to 4 years before He broke the rear.
I've got the 31 spline trak lok 8.8 373 gears from a 96 explorer that I just finished putting into my 66. I've seen comparison charts, and the 31 spline 8.8 rear is literally rated on par (very slightly under) in strength with a built 9" rear. How much are you going to pay for a 9" rear?
As well, I was just going to modify my 8" with a limited slip carrier and 373 gears until i went price searching.....lol!!!!
I got my 8.8 for $150 from the junkyard WITH rear disc brakes WITH 373 gears, WITH 31 spline axles and WITH limited slip/trak lok...I bought summit racing spring perches for $10 or so and had a friend weld them up for free....I've picked up an explorer aluminum driveshaft from a junkyard for $25 which is a direct drop in....OR in the past I've had my stock shaft rebalanced cut and welded, stuffed with new joints for $78. I'm using the explorer shock plates presently...but not happy with the fit...so I plan on using the stock 8" plates...and I'll redrill to accept the wider u bolts.