You have a DV condenser head, but the enlarger appears to be a DII—not a D2.

The DII has a “push-pull” carriage to raise and lower the carriage along the column.

The D2 has a geared elevation crank to adjust the carriage height.

The DII has a unique base column casting with a single large locking knob to secure the column to the base casting as can be seen in photo #2.

You can view the various “Discontinued Enlargers” in the Omega line here along with a description of the accessories and their Omega part numbers.

http://www.khbphotografix.com/omega/

The negative carrier is Condite Manufacturing Precision Negative Carrier for the DII and D2. This is an aftermarket product having nothing to do with the enlarger maker Simmon Brothers Omega.

The rails on the baseboard are also aftermarket. They’re likely to locate a dedicated easel, possibly an easel for handling continuous roll paper.

The following lens mounts are made for the DII:

3400 Flat Mount (for 50-105mm lenses) (later part #421-100)

3408 Flat Mount with threaded cup for 50mm Leica camera lenses) ( later part# 421-021)

3404 Lens Cone 2¾" (for 105mm to 135mm lenses) (later part #421-101)

3406 Lens Cone 4½" (for 150mm to 162mm lenses) (later part #421-102)

For 35mm enlarging you’d need a 40mm wide-angle or a 50mm lens on a flat board.

The 75mm lens is for negatives of 6 x 4.5 cm up to 6 x 6cm but could be used for old 4 x 4cm negatives on 127 film. This also mounts on a flat board.

The 135mm Elgleet is a somewhat wide-angle enlarging lens intended for 4” x 5” negatives. It requires the 2 3/4” lens cone.

Each of these lens boards and cones requires the lens be mounted onto the lens disc, and the lens disc and lens is then mounted onto the appropriate flat board or cone.