To some, Maryland trucker Mark Gunther was a warm-hearted guy, the kind who would drive 150 miles to help a customer bury a dead puppy.

To others, the 41-year-old high school dropout was a hard-driving businessman, someone who was in his truck yard at 5 a.m. on cold winter mornings, trying to heat charcoal to get his rigs running.But a very different picture of Mark Gunther emerged in a Baltimore courtroom last week.

As the man who founded the company that bears his name, he was the one who personally ordered that thousands of driver logs be altered to make them fit federal law - and then lied about his actions.

Barring a successful appeal, Mr. Gunther will be spending the next 30 months in a federal prison to pay for those crimes.

Mr. Gunther's case, brought to a close Friday with the sentence handed down by U.S. District Court Judge William Nickerson, has been watched closely by truckers and safety advocates.

But the case involves more than carton after carton of fudged driver logs, known in some parts of the trucking industry as ''joke books.'' It represents the first successful criminal prosecution of a trucker who refused to live by the government's regulations on permissible driving hours. Those rules require drivers to take eight hours off after spending 10 hours behind the wheel.

The Gunther case is seen by federal prosecutors and safety advocates, including Parents Against Tired Truckers of Lisbon Falls, Maine, as a warning to other companies under pressure from their customers to meet unrealistic delivery schedules. In Mr. Gunther's case, for example, some employees were told to drive up to 20 straight hours to meet promised schedules.

''This court can send a message to the industry that you are putting people at risk,'' said Andrew White, the assistant U.S. attorney who led the government's case. ''This court has the opportunity to save lives. He (Gunther) made a mockery of the whole regulatory system. We have an entire industry watching to see what you (Judge Nickerson) will do. This is a chance to tell the entire industry the rules have changed.''

''Highway deaths can't be treated as a cost of doing business,'' said Daphne Izer of Parents Against Tired Truckers. ''Safety starts at the top. That is where it should have started at Gunther's.''

Mrs. Izer and others organized the truck safety group after relatives and friends died in accidents attributed to fatigued truckers. None of the 2,000 fatigue-related fatalities in 1995 or prior years, however, involved Gunther's.

Mrs. Izer and the three other safety advocates in the courtroom were vastly outnumbered by more than 70 of Mr. Gunther's friends, family and colleagues, several of whom wept after the sentence was passed.

During sentencing, Mr. White produced records showing that one-third of the Gunther company's long hauls in early 1996 - after Mr. Gunther and the firm were convicted - required drivers to exceed allowable service hours.

The investigation into Gunther's activities, conducted by the Federal Highway Administration, focused on the accuracy of driver records during the early 1990s.

Mr. Gunther and his company were indicted in June 1995 on charges of conspiracy to evade agency rules and lying to investigators about thousands of driver records. They were convicted by a jury in December.

The Gunther case dramatizes difficult driver fatigue issues associated with so-called hours-of-service laws, which are being re-examined by the Federal Highway Administration.

New draft rules to supplant the 57-year-old driver service standards are expected imminently.

David Irwin, Mr. Gunther's attorney, read a statement by Ken Buck, Gunther's vice president of sales and marketing, in which he quoted Tom Donohue, American Trucking Associations president, as saying the hours-of-service laws are ''insane.''

''The hours-of-service rules have to be changed,'' said Lana Batts, who heads the Interstate Truckload Carriers Conference, in an earlier interview. ''It's unfortunate that Gunther's case brings it (the rules) up, rather than the underlying issues surrounding hours of service.''

The ATA and the truckload carriers group stressed that they did not condone violations of hourly driving laws. But the trade associations want the laws reviewed with an eye toward wide-ranging changes.

Ms. Batts said a larger issue in fatigue debate is the natural wake/sleep cycles that determine whether workers in trucking - and other transportation industries with irregular schedules - can perform their jobs at top efficiency.

''The hours-of-service rules create fatigue,'' she said. ''We are learning that fatigue is governed by the amount, timing and quality of sleep. The hours-of-service rules have to reflect what we have learned in the past 60 years.''

The case has consequences for the company, Gunther's Leasing Transport Inc. of Hanover, Md., beyond Mr. Gunther's sentence and the government's rules.

Judge Nickerson's fine of $171,000 against Gunther's could present a commercial hurdle even larger than losing its founder for the immediate future. Mr. Gunther was ordered to report to prison on Jan. 6.

Wade Ritchie, a Glen Burnie, Md., accountant, painted a bleak picture of the company's finances. The carrier is past due in payments to major creditors, and two financial institutions are calling in their loans, he testified Friday.

The company's equity, at just $1.5 million, is half of what it was in early 1995, and the firm could face financial ruin in 18 to 20 months, he said.

Mr. White challenged the financial picture painted by Mr. Ritchie, noting that Mr. Gunther and his family were paid a $607,000 bonus in 1994. Mr. Gunther and his wife, the only stockholders, also received $212,000 in bonus pay over the prior three years.

Judge Nickerson ruled that the fine could be paid over four years.

He also reduced the maximum fine under federal sentencing guidelines by $70,000, giving credit for $65,000 paid in fines to the Department of Transportation during the four-year investigation and for a $5,000 contribution by Gunther's to Parents Against Tired Truckers.