hey i am planning on changing out the 305 and putting in an 350 are there any complications to know about ? vaccum lines to trani ? exhaust and i wonder why its hard to go into 4 low ? and when i stop it seems there is a clinking noise ... and what about putting on dual shocks on the front but they want 120 bucks for the bracket on ebay is there a cheaper place to get them ? i have a first gen. (85) with a 4" lift. i amplanning on changing the tie rods and center link i just put on 35" tires with 11" rims and i was told they will eat up parts on the front end should i just keep the 31" tires that are 8" wide they do seem to drive and handle better.
any one out there with knowledge understanding ans wisdom of the 4x4 world i would appreciate your expertease and experience...ben512v.
oh about going into 4 low i seen a vaccum chamber on ebay for 55 bucks i wonder if this could be bad ? all the u joints look new.thanks........

 

Externally, the 305 and 350 are identical (given like years).

As far as 4LO, what transfer case do you have? Are you stopping and putting the transmission into neutral before trying to engage 4LO?

An 85 is not a 1st gen... Unless you are talking about the s-series, but you posted in the fullsize tech...

I remember seeing kits for dual shocks up front, but I cannot remember where. Again, these were for a full size.

 

ok thanks i am new to this site and i will have to learn how to use it.also the 350 motor is a 1979 and the transfere case is i am not sure how do i tell is there a number to look for ? and yes i am stopped but i have to move the vehicle forward or backward then try again before it will go into 4 low say kinda work it in.
what is a 1985 then if not a 1 gen ? i got the brackets figured out thanks......

 

Basic things were no different from 79 to 85. You should compare the accessory drive mounting bolt locations between the two motors though.

As far as the transfer case, it likely is a 208 as this was the only transfer case offered in 85.

When going into 4LO, try it with the vehicle rolling slightly forward. Pop the transmission into neutral and then put the transfer case into 4LO while you are still moving.

 

Fullsize Blazers (K5's) were produced from 1969 through 1994...
69-72 was the first body style, then the 73-79 with their round headlights. 69-75's were fulltops and starting in 1976, Blazers were halftops up to 1991.
1980 was a one off year with the 73-79 front clip but with single square headlights.
81 to mid 88 had the square front ends and four up and down headlights and 88-91 had the four sideways headlights. (except for the very base option which had a single large square headlight)
1992 saw the new body style (1988 for trucks) with the absence of a removable top and the previous solid front axle.
Starting in 1995 the name was changed to "Tahoe" and the GMC Jimmy was changed to "Yukon". The last fullsize 2 door was made in 1999 or maybe 2000, I don't remember for sure. Also, you could get a 2wd up to 1982.
I would consider an 85' fullsize to be a third gen but that's probably debatable.