Converting a post 1975 Chevrolet Full-size Blazer to Full Convertible Hardtop, like the 1973 through 1975 models is an easy afternoon project. I converted my fully loaded 1990 Blazer using parts from a donor 1973 Blazer. The 73 donated the hardtop, upper windshield frame and parts from the doors to the project. It took me and my friends, Josh Westwood and Mark Newhan about five hours to make the swap. Of course additional time and materials were needed to finish prep the Blazer for paint at the A and B-Pillars as well as the doors.
It should be noted that the 1973 through 1975 Blazers had additional support in the form of “Rocker Boxes” under the rocker panels that added to body rigidity. When a post 1975 Blazer has the steal cab removed some body flex will be noticed in the door openings, however the windshield frame, A-pillar and B-pillar are plenty strong, and with the Fiberglass Hardtop on I have noticed no significant flex. This modification does not really affect the strength significantly as the laddered chassis frame is what carries the weight of the vehicle. The flex problem is often fixed by simply replacing body mounts with firmer urethane mounts. Some people have fabricated rocker boxes or “sliders” to stiffen that area of the body. Perhaps the best and only correct solution after having removed the safety of a steal cab is to add a full safety cage that will protect you as well as control the body flex.
1) Remove the windshield glass from both Blazers. Chances are you will crack the windshield.
2) Before cutting the windshield header from the donor Blazer and cutting the cab off of your project Blazer, make careful measurements and mark where your cuts will be made. The windshield frames are the same size and the glass is interchangeable. Measure up from the bottom of the windshield frame on both Blazers and make your marks at the same height. I made my cuts about two thirds up the A-pillar. At the B-pillar, cut flush with the top of the bed rail (in my pictures we cut below the bed rails because the steal cab and my half-top were being reused on a 1975, go figure!) and fill the holes with sheet metal. An easy way to do this is to cut off part of the bed rail from the donor and graft it in. Using the windshield glass as a pattern to confirm fit, tack on the windshield header and install the Hardtop to get the correct alignment with the header.
3) Modify your doors by cutting off the window frames. This can be tricky, so I used doors off a 1975 as a pattern to make templates from cardboard to get the correct angles. Take your time here as there several different compound angles on the upper part of the window frame that need to be cut. Cut long, and grind back to fit.
4) There are brackets in the 73 through 75 doors that need to be salvaged and welded in to your new doors to hold the window track in place and add strength at the top of the door where you cut. The small fiberglass cap also screws down to one of these brackets. If you don’t have them you can easily make something to weld in.
Remember to protect your windows, mirrors, paint and interior from welding splatter and grinding sparks. That’s about all there is to it. I can’t tell you how much I enjoy the drivability of a later model Blazer with TBI and Power everything and in the summer it’s always Fully Topless!
