As others have said, the transmission service isn't that hard. Yours is even better because it will have the torque converter drain plug, so you can drain all of the old fluid out easily. The drain plug for the torque converter disappeared in Sept. of 1999 I believe, so all of the '99 models ought to have it. Yours may not have the pan magnet, so you should add that if it hasn't already been added. The magnets appeared in about 2001. Cost is only about five bucks for the magnet.

__________________
Len
'59 220S Cabriolet-SOLD and living happily in Malta
'83 240D 351,500 miles original owner-SOLD
'88 560SL 41,000 miles - totaled and parted out
https://sites.google.com/site/mercedesstuff/home
'99 E300 turbo 227,500 miles
'03 SLK320 40,000 miles - gave to my daughter
'14 Smart electric coupe 28,500 miles
'14 Smart electric cabriolet 28,500 miles
'15 Smart electric coupe 28,000 miles