Craig, the SD70s and the ES44s use the same parts.
Lionel part #'s
691RS16OHM / ALT 691RESC016 SMOKE ELEMENT / 16 OHM / WIREWOUND $2.00 Ea.
691SMKP008 SMOKE UNIT BATTING / 8" LONG / PRE-CUT FIBERGLASS $2.50 Ea.
Shipping is $10.00 !!
Hope This Helps, Ernie