high four wheel drive problem
 

I have a 1984 K5 blazer with manual locking hubs, well when in four wheel High going about 30
miles per hour it pulls hard left then right then left almost impossible to steer it straight its really dangerous, I can't figure out whats causing it, in two wheel drive its fine and four wheel low is geared so low that you go only about 5 to 10 mph and its not noticeable, any ideas, thanks

Are both wheels the same diameter on the front axle?

yes both tires are the same 33's, I took the locking axle apart but everything looked ok nothing obvious stood out

Are all of the joints in the steering tight? No play?

I jacked up the front end and tried moving the left and right front wheel from side to side and up and down but didn't notice any thing out of the ordinary,

Do you have a steering stabilizer (shock on the steering linkage)? Do you have larger than stock tires?

There is a condition known as the death wobble, but this typically happens at higher speeds and I do not recall it happening only with 4wd engaged...

Will it happen if you do not have the transfer case engaged, but have the front hubs locked in?

I have a new steering stablizer I believe the original tires were smaller, the tires are the same as your picture of the red and white blazer on your post, I'll try to lock the hubs in tomorrow and see if it does it without engaging the transfer case, thanks for your input, I'll let ya know the results

The tires on my K5 are 33x12.5-15s. They are much bigger than stock.

The tires on my blazer are 33x12.5-15s also

I locked in the front hubs in four wheel drive, drove the blazer and its fine, stopped engaged the shifter in 4W/H and it doing the same thing it really jerks you left then when you turn right to compensate it jerks you the opposite direction