ok ive been reading and i see that a v8 will fit in and bolt up to the stock tranny but do i need a newer v8 or does the year matter if so my blazer is a 95 what year motor would give me the least amount of headaches during install

 

using a 95 5.7L (350CI) from a silverado/sierra/fullsize whatever would give you the least amount of heartaches. Computers match up, everything.

Keep reading, you'll need swap mounts, headers (2wd and 4wd headers are different) etc.

 

tons of info out there. it's not a hard swap. goodle s10 350 swap, you will get lots of good links for info/parts/etc.

one part I found hard to figure out is a 4wd you need a conversion oil pan, unless you use the advance adapter 4.3 conversion mounts. but you will need a cowel hood or body lift for that, as the motor gets raised up a bit
I would reccomend the mid 80's camaro 305 manifolds, unless your looking to get the most hp you can out of it, due to clearence reason's, they fit easier then the conversion headers.

google the crap out of it,
this is one reference link I have bookmarked, I am still up in the air if my jimmy will be getting a 350 when the snow is finished
http://www.marquisphotos.com/ZR2_Blazer/V8ZR2/6.htm

2wd's are a lot more clearance friendly.