1987 300E or 1981 300SD - considering buying- need advice

[86560SEL]

I am still in the market for a older Mercedes to use as a work car. I have sold my 95 Chrysler and 93 Camry. I have found two local Mercedes I am considering and going to try to look at them tomorrow. One is a 1987 300E, in VGC for $2100. My cousin has it listed on a local classified site that he has. He has it listed for someone else. I do not know the details, but it is listed as "low miles" (unsure of how many) and said to be in good running shape, with some exterior blemishes. I have also found a blue 1981 300SD that is also supposed to be in GC. Supposed to be rust free, good running. The only flaw the woman was able to tell me about is that the driver seat could use new springs. I think this is very common for 80s Mercedes? That car is priced at $1500 obo. The car belonged to her sisters husband, who suddenly passed away and she is selling his cars. She was asking $2400 a couple of weeks ago. I know it is impossible for an accurate answer- but which would be the better deal- if both were in #3-#4 condition? I think the diesel would probably be more reliable and more fuel efficient- and maybe more comfortable- since it is a larger car. However, the 87 has airbag and ABS- and safety is important to me. I know that a non-airbag 300SD is still a very safe car. I am not at all familiar with Mercedes mechanicals, especially the 300E gas. Are these fairly reliable? What problem areas should I check on both cars- especially the 300E? ANY advice/information appreciated.