There are a number of enlarger that work with 4X5, Omega D 2, 3, and 5, Beseler 45XL with motor that raises and lower the negative stage, LP, Sanders (sp?) and Durst. You can also find very old and hard to use Federals and Dejours. I have a D3, going on 40 years, rugged, easy to find parts, the D2 is more common. The D3 has auto focus rails that matched to specific lens. Mine did not have the matched lens when I bought it so I took the rails off. D5 have a two bellows system that eliminated the needs for lens cones for longer lens. You can try ebay, Shopgood.com for any listed at a Goodwill store near you. Goodwill usally does not ship 4X5 enlargers Craigs List has a D2 in the Boston area.
What you may want to do is download the manuals for the various models to see what you will need. The Omega listed below may not come with the cones for 6X9 and 4X5, a 90mm or 135mm enlarging lens. If you have a 23C you might a safelight, timer, ect.
Simmon Omega Type D-2 Variable Condenser Darkroom Enlarger- Black n White.
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