That is called a "rack and pinion". They are standard and you can buy them "raw" (i.e. I believe you can get it in different lengths and sizes and cut it down to the length you need) from industrial suppliers.
I see that you're in the US, probably the cheapest option would be to buy a HF 1 Ton Press and strip it for parts, because buying rack stock is pretty expensive (see McMaster Carr's website). Alternatively, you might be able to find it less expensive on Ebay as a metal lathe feed rack and cut it to the size you need. Not sure what else you can look under to find it, on Ebay.
But, as someone else pointed out, a different strategy may be better. Using an ACME threaded rod and nut (again, standard sized stocks are available from industrial suppliers) should make it easier for overcoming the pressure, although at the cost of taking additional time to move.