Pierre, that's one of the reasons why people say it's a pain to build, the other is the typical AMT fit quality from that era. Here are some articles on correcting the AMT T600:
https://public.fotki.com/modeltrucks25thscale/model_magazine_articles/car_modeller/cm17_jan_1993_updat/
https://public.fotki.com/modeltrucks25thscale/model_magazine_articles/car_modeller/cm18_mar_1993_updat/
https://public.fotki.com/modeltrucks25thscale/model_magazine_articles/car_modeller/cm19_may_1993_updat/
https://public.fotki.com/modeltrucks25thscale/model_magazine_articles/car_modeller/cm20_july_1993_upda/
https://public.fotki.com/modeltrucks25thscale/model_magazine_articles/car_modeller/cm21_sept_1993_conv/
https://public.fotki.com/modeltrucks25thscale/model_magazine_articles/car_modeller/cm23_jan_1994_updat/
I have yet to try these as it's a daunting project, and I can barely build box-stock. So you know, Gary Wallace from GW Trucks offers the correct T600 front suspension, and a variety of engines that are appropriate for the T600 (Detroit Diesel Series60, Cummins N14, and a yellow engine).