Mr. Pick, if I may call you that...........
OK, let me try to narrow your location down.......You say EAST of Mountain Ave.......The only LV spurs that I am aware of EAST on Mountain Ave. are technically in Piscataway, EAST of South Ave, and WEST of New Market Ave......The first set of sidings are the New Market freight station/Moorecraft Coal/Battelie & Renwick Coal, between New Market Ave. and Prospect St...... The siding had a "dip" to it, but is now removed on the east end.
Now, the siding you are probably thinking of is immediately on the other side of Prospect St., running up a short and steep little hill to get into the company, which I believe is/was a chemical company of some sort. The original name, as well as the current name (if it has changed, that is) escapes me right now, but I will be venturing that way later today, so I'll check. I have seen cars (and an engine) switching it at various times in the last 10 years I have lived here, but I do not know if it currently gets service, I will check to see if I can spot some cars today. See page 111 of Greenberg and Fischers LVRR East Of Mauch Chunk book for a picture of both sidings.
The only other siding (and this qualifies as a spur due to it's length) is the Dismal Brook branch, just around the curve from the last siding. It almost comes down as far as South Ave., as witnessed by covered hoppers fronm the road. I do not know if the name of this spur is a Conrail designation, or an LV one, I will check with a friend who was an ex-employee. I am not familiar with the current shipper or shippers on the spur, but at one time Buffalo Tank, Phoenix Steel Container, and Jersey Steel Drum were located on this spur. There was a bad wreck here in the 1960's with a PA or two in freight service. If I can post a picture of it, I will.
I will report back with more info.......Hope this helps for now,
MP28 on the New York Div.