'86 Burb diff. gear question

[86burb]

Howdy..I'm new to this forum. I am looking for some advice.
I have a 1986 4WD 10 series Burb in great shape. I have to replace the rear diff. gears..(broken tooth on the ring gear)
Gear set is(3.42) 41-12, 8 1/2 " -10 bolt.
I am having a hard time finding a good used set. A friend gave me a complete set of gears but it is a(3.08) 40-13.
The front diff. is OK.. Should I keep looking for 3.42's or put the freebie 3.08's in and look for another set for the front? Which ratio is most common?
The pinion on the 3.08's looks a bit bigger. Any forseen problems with this in my exsisting housing?
As you can probably tell, I'm not an experienced rear end guy,(not with trucks anyway)
I know...I could fork out the $$ and buy some fresh ones, but I'm cheap!!
Any advice would be greatly appreciated.
Thanks in advance, Doug

[tbplus10]

What do you use this truck for mostly? Off-roading or commuting.
The 3.08 is a little bigger diameter wise, but this gear ratio was a factory available ratio for your truck.
3.08's will leave your truck suffering off road, but on road the increase in mpg will make you happier.
3.42's are actually a more popular gear for mid 80's Suburbans, but finding any size used gears is usually an iffy prospect. Most times gears are replaced because they developed problems and have to be replaced. Try looking on some of the off-road boards I know I've seen some for sale recently.

[86burb]

Thanks for the info, Tim..
The truck is used for hiway , pulling a tin boat.and hauling supplies, a work truck mostly. It has a 4 speed auto tranni, with manual hubs. I'll check the off road posts. Cheers, Doug,