I've been out of the frey for the last years, but I concur with Mr. Rider. I've recently been casually researching York and surrounding counties circa 1720-1800 (solely on the net, as I'm on west coast)and have come to the conclusion that if there is more evidence out there for Jacob Arney, it's likely to be written in the German language and held in a special collection. That said, it's also probably not transcribed, nor on the internet.
York only became a county in 1741. Prior to that, one needs to look at surrounding counties that contributed land to the new 'York' county. Since this area was heavily populated by German and Swiss immigrants, the early records are written in German and are mostly religious records. I'd check the Moravian records, now held by the Moravian Org, in Bethlehem, PA, if I could. One needs to go there, or pay a minimum of $50 for a 30 minute research attempt by their staff.
A tidbit of interest I found... From "History of the Kreutz Creek Charge of the Reformed Church" (York County) Jacob ErnyIst gebohren den 12ten Merz 1802. Ist gestoben 28ten Februarius 1816 Alt ward 14 Jahr weniger 2 wochen.
Loosely translated, this Jacob Erny was b. 1802 and died 1816, 2 weeks shy of his 14th birthday.
Also note that it was only AFTER 1730, that the US gov't, required immigrants to register. Prior to that, they were not documenting their arrival. An Arney/Erny etc. could well have immigrated without an arrival record. There were 3 'waves' of immigrants in the first part of the 1700's, from the Swiss, German areas of Europe.