Are you sure the civilian version was called "149"?
In 1984 a smaller version, the 148 was made, modifying a 33 4x4 model of the time. This too had a structural frame and bolted bodywork in order to increase its versatility and make it possible to install weapons such as small canons and heavy machine-guns. A single version was planned with a wheelbase of 210 cm and a length of just 350 cm, front wheel drive with the option of rear wheel drive, 5 (but no reduced) gears. It has McPherson independent forward suspension while at the rear it has a rigid axle. The car's on the road weight is 970 kg and it has a capacity of 430 kg, with a maximum tilt of 60%. Only one model was designed using the boxer 1500cc engine. The 2 off-road prototypes were known at Alfa as Magnaghina (148) and Magnagona (the 146 see
http://www.autopuzzles.com/forum/index.php?topic=12138.msg117922#msg117922 ) They were presented to military authorities in Rome in 1985, driven by Guido Moroni, the same test driver who had demonstrated the Matta 35 years previously.
A press release was circulated in 1986 regarding the probable production of the 148 as a joint venture with Nissan at the Pratola Serra factory as soon as production of the Arna came to an end. Rumors went round about Alfa Romeo being sold and the project was shelved. The 148 was put in the Alfa Romeo Museum where it joined the 146 and they are still there today (although not displayed).
A civil version derived from the Magnaghina was also made, as well as an SUV version. But neither went in production.
In the attachment some pics of the SUV version: