Squarebody handling vs 88-98 trucks?

[yossarian19]

So, I'm thinking about a frame swap for my '57. I have seen EZ Chassis sells a kit to put the '57 bodies on 73-87 frames. Today at the Cars & Coffee I saw a guy with a '57 chevy longbed, same as mine, on a GMT-400 frame that had been shortened, and all the mounts had to be fabbed.
Does the GMT-400 stuff handle enough better / offer enough improvement over a square body to warrant the extra trouble? I realize Im' in the wrong forum for an unbiased response but I thought I'd ask anyway

[D13]

Significantly better primarily due to lighter chassis weight and shortening the amount of truck in from of the wheels. Has a little bit better front geometry, but stilll not what you would think of a 'modern'. Might be better off with the square frame and some upgrades - see the 'make it handle' thread.

[Jeepwm69]

I have an 83 GMC and a 95 GMC, both bone stock.

The 95 drives 100x's better than the 83.

83 has 37K on it, 95 has 52K on it, both bought new, and I started driving the 83 in the late 80's, and the 95 since it was purchased, so it's not like the 83 was worn out and the 95 was new.

The 88-98 is just a much better driving/handling truck.

[yossarian19]

OK, so, Looking at the EZ-Swap page more closely, it looks like the squarebody frames would need to be cut up to fit my longbed. If I go the frame swap route it sounds like the GMT-400 trucks are a better bet, being incrementally more work (body mounts) but a much better result.

[CSHADES]

The front wheel track width is a bit wide for the 55-59 trucks.

[cadillac_al]

Originally Posted by Jeepwm69

I have an 83 GMC and a 95 GMC, both bone stock.

The 95 drives 100x's better than the 83.

83 has 37K on it, 95 has 52K on it, both bought new, and I started driving the 83 in the late 80's, and the 95 since it was purchased, so it's not like the 83 was worn out and the 95 was new.

The 88-98 is just a much better driving/handling truck.

Are we talking 2wd or 4wd? I don't notice a great difference in 2wd's but with 4wd's it's like night and day. I'm still hanging on to my solid axles for a few more years.

[Jeepwm69]

Originally Posted by cadillac_al

Are we talking 2wd or 4wd? I don't notice a great difference in 2wd's but with 4wd's it's like night and day. I'm still hanging on to my solid axles for a few more years.

Both are 2wd.

83 is a 305, SM465. Currently has about 37K on it. Dad let it sit out so it needs paint and a dashpad, but mechanically it's a 37K truck.

95 is a 350 auto. Clean truck.

Both were bought new by the family. My grandad owned the pontiac/buick/gmc dealership here from the late 40's till the early 90's.

The 83 drives like an old truck. The 95 drives like a car. Just completely different feel.

Both are much better than my Jeep CJ's. I like solid axles in a 4wd.

[WyattTX]

I feel silly for asking, but what is wrong with your '57 frame? If you want modern items like a newer engine, better axles, power steering, AC etc. That can all be fabbed and retrofitted on to an old frame, I'd go that route, before I started butchering newer frames.

[WyattTX]

Never fooled with a gmt400, but my '85 square has never felt too much worse than a modern truck. It's quite comfortable in fact. The best handling truck I ever drove was a 2005 GMC yukon xl. That one felt like a car, though that was a gmt800, not a gmt400.

[yossarian19]

The '57 frame is fine for 1957. My thinking is that by the time I'm done tearing out the riveted-on suspension mounts (front and rear) and replacing that mess with modern components that will do the speeds I want the truck to do, then moving my v8 (which I placed wrong the first time) and boxing things in and, and, and... Maybe it's easier to drop the sheet metal on something that's more than strong enough, has the ride height I want, handles well and has plenty of parts support.
The trick is that I'm already running and driving the ls swap in my 57. It'd really sting to scrap all the work that I've already put into the OEM frame / suspension, but on the other hand, it drives like crap the way it is.

[86LT1C10]

Originally Posted by CSHADES

The front wheel track width is a bit wide for the 55-59 trucks.

I have heard that a lot. I have a '58 and had a 84 long bed frame just laying around and thought I'd do some measuring back a few years ago. This is what I found out. The difference in the width of the two frames is minimal. 1/32 to maybe 1/16in. So with some free time on my hands, I decided to marry the two. I took tons of pics of the process but they are on a different computer that is boxed up right now. I have since put off working on the 58 but I took some quick pics of how it sits today. These 3 are of the drivers side w/ a 275/60r15 tire on the 80's 15x8 rim. It may sit wide for some people's taste but different rim sizes/offsets can easily fix that.

[86LT1C10]

Here are ones of the passenger side with a 90's aluminum 15x7 w/ a 235/75r15. As you can see, a world of difference. My plan was to use the 15x6 rally that was used on the 88-91 vans. (Now I don't know why when I upload these images why they are turned wrong but if you download them and rotate them you will see that the wheel sits in nicely)

[86LT1C10]

Now to explain these pics:
#1 The only modification I had to do to the front of the frame to make the body sit down on it. This is at the radiator support area. I also removed the crossmember that sits below the fan. I never got to fabricating a replacement crossmember.
#2 I had to cut a little off of the inner fender to clear the upper A arms.
#3 I used the 80's steering column mated to a 80's Monte Carlo lower shaft to hook to the gear box.
#4 I ground off the 80's cab mounts and bolted the original 58's cab mounts to the frame. You can also see the two frames mated together.
#5 I boxed in the inner side of the frame channel.

I don't see why a complete frame couldn't be used since the stepside beds between the years are virtually identical in how they mount. At the very least, nothing a little modification can't fix. The only reason I did't try it myself is the front clip was from a longbed.

All in all, I would go for the Square Body style. the frames are tougher than the 90's. The reason the 90's are smoother riding is because GM was trying to catch the female market and women wanted that Cadillac ride. When doing this, they lost the toughness of the suspension and frame. That's why in the 90's Ford kicked GM's butt in commercial sales and twin I beam ruled for once.

[andrewmp6]

I have drove and rode in both trucks to me they are pretty much even.But the square has a better aftermarket for handling if thats what you want in the end.

[Tom]

I don't feel a handling difference. Comfy difference yes, but at the limit handling differences no.

[Gmc.guy]

I was going to do this too years ago, I had a 63 with a wasted frame and measured up a 93 to see what it looked like The 88-98 frames are wider than the earlier ones. They kick out on each side under the firewall and under the cab I'm not remembering exactly how much but it was 5 or 7 inch on each side It put the cab mounts directly on the frame

[finewayne]

no handling difference I guess