I did this conversion on my 3-window cab. It requires a 5-window donor cab,
and is definitely not for the beginning welder, but it worked out well.
There are probably other methods , but this is how I did it. It is a little
hard to explain, but the trick, if you can call it that, is to understand
how the cabs are assembled and plan exactly how it will all go together,
before you start cutting any sheet metal.
Note that the cab corners are double wall from the rear headliner track
down to the beltline. The inner sections of the corners are spotwelded on
vertical seams next to the center window, and at the door-pillar post. These
dimensions and seams are the same on both 3-window and 5-window cabs. So,
this is the logical place to orient the conversion.
I found a donor cab that was a rust out everywhere else but the corner
window area was OK. Cut the corner window area from the door pillar post to
the center window, then along the beltline, and up into the roof area, above
rear headliner track where the inner cab wall begins. You can use a sawzall,
cutoff wheel, or whatever. So now you have the two corner sections on your
garage floor. These are double wall sections.
What you are going to do is use these as "plugs" to replace the corners
in your 3-window cab. The "plugs" will be inserted from inside the cab.
Start trimming these plugs on the outer wall down to about 1/2"- 3/4" from
the reveal around the glass opening. Cut the inner walls on the
aforementioned seams. Your plugs are now ready to use.
On the inside of your 3-window cab, cut out the spot welds along the same
vertical seams as you did on the plugs, and remove the inner cab wall
pieces. Carefully mark the outer wall and cut along the same lines as your
"plugs". At this point it is better to remove too little than too much. You
can remove the excess a little at a time as you trial-fit the plugs from the
inside. Take your time. If done right, you will end up with a near-perfect
fit on the outer seams, which means minimal welding and filling.
Before welding the inner wall to the pillar post, add a couple of seat belt
anchors to the post (about earlobe level). Then when everything lines up OK
on both inside and outside, spotweld the plugs in place inside at the
vertical seams. Then, the outer seams must be carefully butt-welded
together. Voila! you now have a 5-window cab. A little body filler on the
inner seams, grinding and filler on the outside, and you'll be ready to
start looking for decent corner glass (good luck)!
This conversion is a lot of work but definitely worth the effort. Like you,
I always liked the looks of the 5-window cabs. A bonus is the increased
visiblity for that quick over-the shoulder glance before changing lanes.
You can see how the finished product turned out at:
Jack / Winter Park FL
----- Original Message -----
From: "Michael Lubitz" <email@example.com>
To: "Old chevy truck advice" <firstname.lastname@example.org>
Sent: Sunday, April 02, 2000 8:16 AM
Subject: [oletrucks] Conversion from three window to five window
> Hello everyone,
> I have just started receiving messages from "oletrucks."
> I am thinking of purchasing a 3 window 3100, but my heart has always been
> set on a 5 window with side mounted spare. I have been looking for a
> special kind of dainly driver that looks stock and has all of the creature
> comforts and this truck comes the closest after months of searching.
> Without too much in the way of judging my idiocy, does someone know the
> steps to change a 3 to a 5? Is there a kit? Does the whole corner have
> be removed and replaced? Is it an almost impossible task? What might it
> cost in terms of time or dollars?
> Thanks in advance to anyone that responds.
> Michael Lubitz
> > oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959