My first square body...1978 GMC Sierra Classic

[Mr.Rogers]

So I just purchased my first square body, it’s a*78 GMC Sierra Classic 1500 LWB pickup and I love it. I am going to be using it for daily driving and to tow my Harleys occasionally. After searching for almost a year I found the perfect truck for me and my needs. I pop the hood and I find dual batteries and the proper isolator wiring, fresh spark plug wires, a clean distributor cap, long tube headers, clean air filter, I see that is has factory air (that works), and although there were some spider webs and a little debris it was very very clean. I look to the rear end and I see dual flowmaster mufflers, I notice that it is riding somewhat high for a 2wd so I count out 11 leafs in the leaf spring pack, Monroe Air Shocks, and ride assist airbags. I look upfront and it has the disc brakes, a sway bar, Rancho shocks, and all the bushings are look to be in good condition. After pumping the gas pedal a couple of times it lit right up and roared to life. The interior could use some TLC but taking into account that it is an original almost 40 year old truck I can live with that. All in all I feel like I got one hell of a good deal when I consider that I purchased it from the son of the original owner for only $1,800.00.

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After driving everyday it for the last week I have no real complaints but I have noticed a few things:

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It does a have a bit of an oil leak so I need to figure out the source of the leak. Any insight would be helpful.

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The AC gets cold but could blow stronger so I will most likely replace the blower motor and the resistor.

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The suspension is REALLY stiff and there is a lot of hard bounce when I go over any small or big bump in the road. Thr truck starts to acts as a seesaw almost and i have to apply my brakes to come out of it. So I need to figure this out ASAP plus I want to lower it but I am think of only a 2.5/4 drop and sit it on 18’s or 20’s with a nice amount of sidewall on the tires. To obtain that drop I was thinking of replacing all the shocks then doing 2.5 drop spindles up front and just removing 2 or 3 of the leafs in the rear to get that desired drop in the rear but will keep the ride assist bags to help with any load I may trailer and also install a sway bar in the rear. However, I will take any and all help in this department.

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Yesterday after getting off work I went to start it up so I could go home and nothing. I ended up jumping it and turned over so I went to Napa to have them test both batteries and my system. I was told that each battery failed and then they said that each battery passed (makes no sense), then after they jumped the truck again and it turned over they tested the system and told me that my voltage passed, the diodes passed, but output failed. This leads me to believe my alternator may be failing but I was going to get home*today*and take both batteries out and take out the alternator and have them checked individually and see what the read out is. Depending on that I will either replace the alternator or replace both batteries. Let me know if I am on the right path with my thought process.

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Again, this is my first square body and I can use any and all input that you all have to offer up. Thanks in advance!