Front Bumper questions

[SUX2BU99]

I want to replace the front bumper on my truck. I'm pretty sure it's an 81-newer front bumper from it's shape and the fact it had a newer chin spoiler on it. But, I feel my frame might be an 80-down as I don't see the lightening holes in the front crossmember (is that where they are?), my cab bushings I took out were the old style, the tilt column I have is the old style and the rear diff I took out from it had GM 73 stamped on it.

How can I determine a) what year of frame I have and b) what style of bumper horns I have? Seems that my truck is a bit of a mutt. VIN from the cab comes back as an 81 GMC and that's what it's titled as.

I found a 79 and 80 front bumpers locally but want to know before I buy.

[Captkaos]

From what you described, it is a 73-80 frame.  Take a picture and post it (did you trade this truck?)

[SUX2BU99]

Here's a pic of when I did the bushing replacement:


This is a pic of the front though. That's a 81+ bumper, no?


I don't have any other good pics of my frame. Where are the lightening holes on an 81+ frame? I remember seeing a pic of a bare frame somewhere but can't recall if what I'm thinking of is the front crossmember.

No, same truck I've always had. It's an 81 GMC (cab at least) that was redone as an 85 Silverado.

I was incorrect about the rear diff thing. The GM 73 diff was the one I bought last year from the junkyard. I don't recall what my original diff said.

[ccz145a]

My 75 had the vin stamped on the frame, left side top rail between the engine mount and the cab. Maybe your's would have the vin stamped like that somewhere.

[zieg85]

Your bumper is actually 1983 or newer.

[Captkaos]

The middle crossmembers will have holes in them in the brace right behind the bumper and where you Combo valve mounts.  You bumper is an 83-87(91) bumper as Zieg85 stated.

[SUX2BU99]

Like the holes in this crossmember? This is from Vile's Mutt Project thread:



I thought 89-91 bumpers all had those rub strips on them. I really like my bumper but it's tweaked.

[Captkaos]

yes, simular to those.  Rub strips were options on high trim levels.

[SUX2BU99]

I took some pics last night. I think I have a 80-down frame yet have an 83-up bumper. I attached some pics of the bumper mounts too. What kind of work would be involved in getting the newer bumper to work on the older frame?

[80stepsideguy]

Definately looks like a 73-80 frame from the last picture.If you can take a pic of the front bodymount on the core support.73-80 shared the same mounts as 81-7 did. The 73-80 mounts can only go on 73-80 frames as 81-7s do the same as well.

thanks
pat

[Captkaos]

That is a 73-80 frame.

[SUX2BU99]

Thanks guys. I wonder then how the guy who restored it got the 81-up bumper mounts on there? You can just slightly see the body bushing mount in the first pic, ahead of the bumper brace. I know I had to get 73-80 body bushings for it.

[Captkaos]

You just cut the frame to put a 81-87 bumper on it.

[SUX2BU99]

I've been looking over my bumper situation and I've always thought it my bumper that's bent but now I'm thinking it has more to do with the supports, since they weren't stock to the truck. My bumper sits very tight to my driver fender, to the point where this is a contact scratch on the marker light. The passenger side has a big gap. There is also an uneven fore/aft gap between the bumper and the grille/filler panel. The gap is larger on the driver side, to the point where I can easily fit my thumb sideways between with room to spare. Passenger side I can't even get my pinky finger to the end. It's funny because you would think "holy cow, this truck must look totally screwed up but if you weren't looking for the misalignments you might not notice them.

My plan this weekend is to take the bumper off since I'm prepping to change the core support anyway. I figured maybe some small sledge work on a 2x4 might shift the bumper more to the driver side. I have a feeling my bumper mounts are not entirely straight and true to where they should be. I was going to take mount-frame measurements on each side and see if they match.

[SUX2BU99]

I'll retract a portion of what I said above. I know for sure that my bumper IS tweaked on the driver side. The bumper is supposed to curve with the bumper at the bumper ends and on the drivers side it doesn't. It bends about 90 degrees. Also on my bumper mount pic above you can see only one bolt holding it to the side of the frame, not 2. At least the other bolt that goes in from up top is there to position it  lol