Perhaps the front engine was there to drag it home if the rear engine failed?

Here's a page with a lot of inline 6 devices. Argentinian F1 in the early seventies, just click on the thumbnails for more useful picture size:

http://www.info-maf1.facundogalella....racion1972.php

Falcon, Jeep (Tornado), Chevrolet and Chrysler Slant sixes were the engines in most of them.