What are all the parts needed for complete front end?

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2 out of 3 mechanics say I need to replace my entire front end on my 1995 Ranger 3.0 v6 4WD in order to get my four wheel drive to work and for it to handle properly. One says he will replace my front end and says he can get all parts as one...only one ball joint...for $250.. + labor. However, another mechanic says you need everything from upper and lower control arms and ball joints on both sides (driver side is much worse) and differential/housing etc. So exactly if I want it done correctly what parts do I get from junk yard and which parts from store?? I am not sure of gear ratio...I did buy a rear differential cover that was 7.5" the tag is no longer on rear end. So how do I find out?