Slant six?.................
An inline six inclined at a slant of 30 degress from vertical.

As others indicated, it was just a I-6 laid over on it’s side a bit. The reason why was to accomodate the intake/exhaust manifolds on the driver’s side of the engine. This gave the engine more guts than it would have had. It also lowered the cg and hood profile a bit, something that the V-6/8 types have been obsessed with for years.
As an engine, it was a gutsy little thing, with quite a torque-y snap to it. We had one in a Plymouth Barracuda. What I remember most about that car was that it was very snappy off the line and the huge, huge, huuuuuge expanse of glass in the rear window.
I’d go for a slant-six over any V-6 in a New York Minute.
Yup. Three on the tree. Two door. Kind of a Robin’s Egg Blue.