I've run across E48s in M-body cop cars. Actually, they were taxis that started out as TX DPS cars by the time I came across them. IIRC, the engines were 318s with roller cams and 360 heads. The carburetor was a non-feedback, electric choke Q-jet. I recall diving in on an old Diplomat (I was after the Firm Feel steering box) and was surprised to find a Rochester and not a Carter TQ sitting atop the engine. Later conversation with a DPS mechanic confirmed that's the way they got them. He reported they ran pretty well and had no annoying quirks.
